Hide metadata function for in decl_event, and add doc for GenesisConfig (#5431)

* hide metadata function for non generic event

* add doc for decl_storage

substrate/frame/support/procedural/src/storage/genesis_config/mod.rs

@@ -66,6 +66,7 @@ fn decl_genesis_config_and_impl_default(
 	let genesis_where_clause = &genesis_config.genesis_where_clause;
 
 	quote!(
+		/// Genesis config for the module, allow to build genesis storage.
 		#[derive(#scrate::Serialize, #scrate::Deserialize)]
 		#[cfg(feature = "std")]
 		#[serde(rename_all = "camelCase")]
@@ -138,6 +139,7 @@ fn impl_build_storage(
 	quote!{
 		#[cfg(feature = "std")]
 		impl#genesis_impl GenesisConfig#genesis_struct #genesis_where_clause {
+			/// Build the storage for this module.
 			pub fn build_storage #fn_generic (&self) -> std::result::Result<
 				#scrate::sp_runtime::Storage,
 				String

substrate/frame/support/src/event.rs

@@ -288,6 +288,7 @@ macro_rules! __decl_generic_event {
 		}
 		impl<$( $generic_param ),* $(, $instance)?> RawEvent<$( $generic_param ),* $(, $instance)?> {
 			#[allow(dead_code)]
+			#[doc(hidden)]
 			pub fn metadata() -> &'static [$crate::event::EventMetadata] {
 				$crate::__events_to_metadata!(; $( $events )* )
 			}