Add remaining missing docs in System (dotnet#10373)

* Add remaining missing docs in System

* Apply review comment

Author: buyaa-n

xml/System/Delegate+InvocationListEnumerator`1.xml

@@ -85,8 +85,8 @@
       </ReturnValue>
       <Parameters />
       <Docs>
-        <summary>Implements IEnumerable.GetEnumerator() to return  'this' as the IEnumerator.</summary>
-        <returns>To be added.</returns>
+        <summary>Implements IEnumerable.GetEnumerator() to return 'this' as the IEnumerator.</summary>
+        <returns>An IEnumerator instance that can be used to iterate through the invocation targets of the delegate.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -108,7 +108,7 @@
       <Parameters />
       <Docs>
         <summary>Implements the IEnumerator pattern.</summary>
-        <returns>To be added.</returns>
+        <returns><see langword="true" /> if the enumerator was successfully advanced to the next element; otherwise, <see langword="false" /> if the enumerator has passed the end of the collection. </returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>

xml/System/Delegate.xml

@@ -1878,13 +1878,11 @@ The number, order, or type of parameters listed in <paramref name="args" /> is i
         </Parameter>
       </Parameters>
       <Docs>
-        <typeparam name="TDelegate">To be added.</typeparam>
-        <param name="d">To be added.</param>
+        <typeparam name="TDelegate">Delegate type being enumerated.</typeparam>
+        <param name="d">The delegate being enumerated.</param>
         <summary>Gets an enumerator for the invocation targets of this delegate.</summary>
-        <returns>To be added.</returns>
-        <remarks>This method returns a <see cref="T:System.Delegate.InvocationListEnumerator`1" /> that follows the IEnumerable pattern and thus can be used in a C# 'foreach' statement to retrieve the invocation targets of this delegate without allocations.
- The order of the delegates returned by the enumerator is the same order in which the current delegate invokes the methods that those delegates represent.
- The method returns an empty enumerator for <see langword="null" /> delegate.</remarks>
+        <returns>A <see cref="T:System.Delegate.InvocationListEnumerator`1" /> that follows the IEnumerable pattern and thus can be used in a C# 'foreach' statement to retrieve the invocation targets of this delegate without allocations. The method returns an empty enumerator for <see langword="null" /> delegate.</returns>
+        <remarks>The order of the delegates returned by the enumerator is the same order in which the current delegate invokes the methods that those delegates represent.</remarks>
       </Docs>
     </Member>
     <Member MemberName="Equals">

xml/System/MemoryExtensions+SpanSplitEnumerator`1.xml

@@ -34,7 +34,7 @@
     </Attribute>
   </Attributes>
   <Docs>
-    <typeparam name="T">To be added.</typeparam>
+    <typeparam name="T">The type of items in the <see cref="T:System.MemoryExtensions.SpanSplitEnumerator`1" />.</typeparam>
     <summary>Enables enumerating each split within a <see cref="T:System.ReadOnlySpan`1" /> that has been divided using one or more separators.</summary>
     <remarks>To be added.</remarks>
   </Docs>

xml/System/MemoryExtensions.xml

@@ -4368,11 +4368,11 @@ If `source` and `destination` overlap, this method behaves as if the original va
         </Parameter>
       </Parameters>
       <Docs>
-        <typeparam name="T">To be added.</typeparam>
+        <typeparam name="T">The type of elements in the span.</typeparam>
         <param name="span">The span to search.</param>
         <param name="value">The value to compare.</param>
         <summary>Determines whether the specified value appears at the end of the span.</summary>
-        <returns>To be added.</returns>
+        <returns><see langword="true" /> if <paramref name="value" /> matches the end of <paramref name="span" />; otherwise, <see langword="false" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -4964,7 +4964,7 @@ Invalid sequences will be represented in the enumeration by <xref:System.Text.Ru
         <param name="span">The span to search.</param>
         <param name="values">The set of values to search for.</param>
         <summary>Searches for the first index of any of the specified substring values.</summary>
-        <returns>To be added.</returns>
+        <returns>The first index of any of the specified values, or -1 if none are found.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -5001,7 +5001,7 @@ Invalid sequences will be represented in the enumeration by <xref:System.Text.Ru
         <param name="span">The span to search.</param>
         <param name="values">The set of values to search for.</param>
         <summary>Searches for the first index of any of the specified substring values.</summary>
-        <returns>To be added.</returns>
+        <returns>The first index of any of the specified values, or -1 if none are found.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -9787,11 +9787,11 @@ Invalid sequences will be represented in the enumeration by <xref:System.Text.Ru
         </Parameter>
       </Parameters>
       <Docs>
-        <typeparam name="T">To be added.</typeparam>
+        <typeparam name="T">The type of elements in the span.</typeparam>
         <param name="span">The span to search.</param>
         <param name="value">The value to compare.</param>
         <summary>Determines whether the specified value appears at the start of the span.</summary>
-        <returns>To be added.</returns>
+        <returns><see langword="true" /> if <paramref name="value" /> matches the beginning of <paramref name="span" />; otherwise, <see langword="false" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>

xml/System/Type.xml

@@ -6135,12 +6135,20 @@ One of the elements in the <paramref name="types" /> array is <see langword="nul
         <Parameter Name="types" Type="System.Type[]" Index="3" FrameworkAlternate="net-9.0" />
       </Parameters>
       <Docs>
-        <param name="name">To be added.</param>
-        <param name="genericParameterCount">To be added.</param>
-        <param name="bindingAttr">To be added.</param>
-        <param name="types">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="name">The string containing the name of the method to get.</param>
+        <param name="genericParameterCount">The number of generic type parameters of the method.</param>
+        <param name="bindingAttr">A bitwise combination of the enumeration values that specify how the search is conducted.
+
+ -or-
+
+ <see cref="F:System.Reflection.BindingFlags.Default" /> to return <see langword="null" />.</param>
+        <param name="types">An array of <see cref="T:System.Type" /> objects representing the number, order, and type of the parameters for the method to get.
+
+-or-
+
+An empty array of <see cref="T:System.Type" /> objects (as provided by the <see cref="F:System.Type.EmptyTypes" /> field) to get a method that takes no parameters.</param>
+        <summary>Searches for the specified method whose parameters match the specified generic parameter count and argument types, using the specified binding constraints.</summary>
+        <returns>An object representing the method that matches the specified generic parameter count, argument types, and binding constraints, if found; otherwise, <see langword="null" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>