tools/net/ynl-gen-rst: Sort the index of generated netlink specs

The index of netlink specs was being generated unsorted. Sort the output
before generating the index entries.
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://lore.kernel.org/r/20231215093720.18774-12-donald.hunter@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

tools/net/ynl/ynl-gen-rst.py

@@ -383,7 +383,7 @@ def generate_main_index_rst(output: str) -> None:
 
     index_dir = os.path.dirname(output)
     logging.debug("Looking for .rst files in %s", index_dir)
-    for filename in os.listdir(index_dir):
+    for filename in sorted(os.listdir(index_dir)):
         if not filename.endswith(".rst") or filename == "index.rst":
             continue
         lines.append(f"   {filename.replace('.rst', '')}\n")