add the requested comments

Author: soheilshahrouz

libs/librrgraph/src/io/rr_graph_reader.h

@@ -41,6 +41,11 @@ void load_rr_file(RRGraphBuilder* rr_graph_builder,
  * @details This function tries to find a switch with the overridden delay. If such a
  *          switch exists, the edge will point to it as its corresponding switch.
  *          Otherwise, a new switch is created so that the edge can point to a valid switch.
+ *          The architecture file allows the user to specify nominal switch delays, but delays
+ *          may vary for the same switch type across the device. To represent switch delays
+ *          more accurately, the user can specify multiple switch types in the architecture file
+ *          and restrict each one to a region or a single location. Alternatively, the user can
+ *          use this file to override edge delays.
  *
  * @param filename The text file to be ingested by this function.
  * @param rr_graph_builder Used to add switches and override switch IDs for edges.

vpr/src/base/read_options.cpp

@@ -1775,8 +1775,11 @@ argparse::ArgumentParser create_arg_parser(const std::string& prog_name, t_optio
         .show_in(argparse::ShowIn::HELP_ONLY);
 
     file_grp.add_argument(args.read_rr_edge_override_file, "--read_rr_edge_override")
-        .help(
-            "The routing resource edge attributes override file to load.")
+        .help("The routing resource edge attributes override file to load. "
+              "This file overrides edge attributes in the routing resource graph. "
+              "The user can use the architecture file to specify nominal switch delays, "
+              "while this file can be used to override the nominal delays to make it more accurate "
+              "for specific edges.")
         .show_in(argparse::ShowIn::HELP_ONLY);
 
     file_grp.add_argument(args.write_rr_graph_file, "--write_rr_graph")