Merge pull request #17892 from RohanTalip/HandlerParameter-doc

Renamed the param in the documentation for HandleParameter to match the actual parameter.

include/grpcpp/impl/codegen/rpc_service_method.h

@@ -46,7 +46,7 @@ class MethodHandler {
     /// \param context : the ServerContext structure for this server call
     /// \param req : the request payload, if appropriate for this RPC
     /// \param req_status : the request status after any interceptors have run
-    /// \param rpc_requester : used only by the callback API. It is a function
+    /// \param requester : used only by the callback API. It is a function
     ///        called by the RPC Controller to request another RPC (and also
     ///        to set up the state required to make that request possible)
     HandlerParameter(Call* c, ServerContext* context, void* req,