Update toUpperCase.adoc

Capitalized String as discussed with CMaglie. Fixes #6486

Author: SimonePDA

Language/Variables/Data Types/String/Functions/toUpperCase.adoc

@@ -17,7 +17,7 @@ subCategories: [ "StringObject Function" ]
 
 [float]
 === Description
-Get an upper-case version of a String. As of 1.0, toUpperCase() modifies the string in place rather than returning a new one.
+Get an upper-case version of a String. As of 1.0, toUpperCase() modifies the String in place rather than returning a new one.
 [%hardbreaks]
 
 
@@ -55,4 +55,4 @@ None
 [role="example"]
 * #EXAMPLE# link: https://www.arduino.cc/en/Tutorial/BuiltInExamples#strings[Built-in String Tutorials]
 --
-// SEE ALSO SECTION ENDS
+// SEE ALSO SECTION ENDS