Add note about new config.toml file into --help

gcalcli/argparsers.py

@@ -293,12 +293,18 @@ class RawDescArgDefaultsHelpFormatter(
   %(prog)s supports a few other configuration mechanisms in addition to
   the command-line arguments listed below.
 
-  $GCALCLI_CONFIG={config_dir!r}
+  $GCALCLI_CONFIG={config_dir}
     Path to user config directory.
     Note: this path is also used to determine fallback paths to check
     for cache/oauth files to be migrated into their proper data dir
     paths.
 
+  {config_file}
+    A toml config file where some general-purpose settings can be
+    configured.
+    Schema:
+    https://raw.githubusercontent.com/insanum/gcalcli/HEAD/data/config-schema.json
+
   gcalclirc @ {rc_paths}
     A flag file listing additional command-line args to always pass,
     one per line.
@@ -311,14 +317,26 @@ class RawDescArgDefaultsHelpFormatter(
 @parser_allow_deprecated(name='program')
 def get_argument_parser():
     config_dir = env.default_config_dir()
-    rc_paths = [pathlib.Path(config_dir).joinpath('gcalclirc')]
+    # Shorten path to ~/PATH if possible for easier readability.
+    tilde_home = pathlib.Path('~')
+    try:
+        tilde_relative = config_dir.relative_to(
+            tilde_home.expanduser(), walk_up=False)
+        config_dir = tilde_home.joinpath(tilde_relative)
+    except ValueError:
+        pass
+    rc_paths = [config_dir.joinpath('gcalclirc')]
     legacy_rc_path = pathlib.Path.home().joinpath('.gcalclirc')
     if legacy_rc_path.exists():
-        rc_paths.append(legacy_rc_path)
+        rc_paths.append(tilde_home.joinpath('.gcalclirc')
+                        if tilde_home.expanduser() == pathlib.Path.home()
+                        else legacy_rc_path)
 
     parser = argparse.ArgumentParser(
         description=DESCRIPTION.format(
-            config_dir=config_dir, rc_paths=', '.join(str(p) for p in rc_paths)
+            config_dir=config_dir,
+            config_file=config_dir.joinpath('config.toml'),
+            rc_paths=', '.join(str(p) for p in rc_paths)
         ),
         formatter_class=RawDescArgDefaultsHelpFormatter,
         fromfile_prefix_chars='@',