Avoid the -Wdocumentation-unknown-command warning in Clang's C API docs

rdar://20441985


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@299650 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang-c/Index.h

@@ -4034,8 +4034,8 @@ CINDEX_LINKAGE unsigned clang_Cursor_getObjCDeclQualifiers(CXCursor C);
 
 /**
  * \brief Given a cursor that represents an Objective-C method or property
- * declaration, return non-zero if the declaration was affected by "@optional".
- * Returns zero if the cursor is not such a declaration or it is "@required".
+ * declaration, return non-zero if the declaration was affected by "\@optional".
+ * Returns zero if the cursor is not such a declaration or it is "\@required".
  */
 CINDEX_LINKAGE unsigned clang_Cursor_isObjCOptional(CXCursor C);
 
@@ -4711,7 +4711,7 @@ enum CXCompletionChunkKind {
    */
   CXCompletionChunk_HorizontalSpace,
   /**
-   * Vertical space ('\n'), after which it is generally a good idea to
+   * Vertical space ('\\n'), after which it is generally a good idea to
    * perform indentation.
    */
   CXCompletionChunk_VerticalSpace