Print actionable error message when --check finds stale files

Previously both update-sig-tables.py and update-community-members.py
silently exited with code 1 when run in --check mode and the generated
file was out of date, making CI failures hard to diagnose. Now they
print a clear message to stderr naming the file and the remediation
command ('make generate').

Signed-off-by: immanuwell <pchpr.00@list.ru>

Author: immanuwell

scripts/update-community-members.py

@@ -66,6 +66,7 @@ def splice(content, start_marker, end_marker, body):
     if original == result:
         sys.exit(0)
     else:
+        print(f"{MARKDOWN_FILE} is out of date. Run 'make generate' to update it.", file=sys.stderr)
         sys.exit(1)
 else:
     with open(MARKDOWN_FILE, "w", encoding="utf-8") as f:

scripts/update-sig-tables.py

@@ -171,6 +171,7 @@ def render_group(group_name, sigs, show_sponsors):
     if original == result:
         sys.exit(0)
     else:
+        print(f"{markdown_file} is out of date. Run 'make generate' to update it.", file=sys.stderr)
         sys.exit(1)
 else:
     with open(markdown_file, "w", encoding="utf-8") as f: