Add clarifying comment

Author: unstubbable

crates/next-custom-transforms/src/transforms/server_actions.rs

@@ -249,7 +249,11 @@ struct ServerActions<C: Comments> {
     annotations: Vec<Stmt>,
     extra_items: Vec<ModuleItem>,
     hoisted_extra_items: Vec<ModuleItem>,
+
+    // A map of all server references (inline + exported): export_name -> reference_id
     reference_ids_by_export_name: FxIndexMap<Atom, Atom>,
+
+    // A list of server references for originally exported server functions only.
     server_reference_exports: Vec<ServerReferenceExport>,
 
     private_ctxt: SyntaxContext,