Merge pull request #26616 from varungandhi-apple/vg-add-isGeneric-doc-example

Add a couple of examples to the isGeneric() documentation.

Author: rjmccall

include/swift/AST/Decl.h

@@ -1523,6 +1523,17 @@ class GenericContext : private _GenericContext, public DeclContext {
 
   /// Determine whether this context has generic parameters
   /// of its own.
+  ///
+  /// \code
+  /// class C<T> {
+  ///   func f1() {}    // isGeneric == false
+  ///   func f2<T>() {} // isGeneric == true
+  /// }
+  ///
+  /// protocol P { // isGeneric == true due to implicit Self param
+  ///   func p()   // isGeneric == false
+  /// }
+  /// \endcode
   bool isGeneric() const { return GenericParams != nullptr; }
 
   /// Retrieve the trailing where clause for this extension, if any.