provide / inject

Author: yyx990803

src/api/composition-api-dependency-injection.md

@@ -44,4 +44,6 @@
 - **See also**:
   - [Provide / Inject](/guide/components/provide-inject.html)
 
-## inject()
+## inject()
+
+// TODO

src/api/options-composition.md

@@ -132,6 +132,8 @@
 
 ## inject
 
+// TODO
+
 ## mixins
 
 - **Type:** `Array<Object>`
@@ -189,4 +191,4 @@
     extends: CompA,
     ...
   }
-  ```
+  ```