l2md: add todo file to keep track of future improvements

Add two more suggestions from Konstantin with regards to using the
manifest file for checking updates and epoch roll-over.

Suggested-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
diff --git a/TODO b/TODO
new file mode 100644
index 0000000..23e931a
--- /dev/null
+++ b/TODO
@@ -0,0 +1,12 @@
+- Add option to use manifest file from https://lore.kernel.org/manifest.js.gz
+  instead of periodically probing git fetch to check for new mail. This would
+  allow to compare "fingerprint" or "modified" entries to see if the repos
+  actually changed. The "fingerprint" entry is just `git show-ref | sha1sum`,
+  which is deterministic.
+
+- Using the manifest file will additionally help to automatically recognize
+  epoch roll-over. It does not happen very frequently, but it does happen --
+  0.git will eventually stop being updated and become 1.git, etc. Relying on
+  the manifest, one will be able to automatically recognize when such event
+  occurs and therefore it wouldn't need to be manually enabled in the l2md
+  configuration file.