write "not implemented" section

README.md

@@ -65,3 +65,19 @@ $ export SQLITE_DB_PATH=archive.db
 $ export STORAGE=storage
 $ mitmproxy -s addon.py
 ```
+
+# What's not implemented
+- Filter host instead of archiving everything (literally 2 lines of code, could be added soon after I figure out the best way to configure this)
+- Addon is configured with env vars, Server uses command-line options; should be unified?
+
+Probably useful, but would overcomplicate the project:
+- Alphabetically sort query arguments both in addon and server (for now if archive contains `/api?key=val&abc=def`, the same request `/api?abc=def&key=val` gives 404, because URL is not exactly the same)
+
+Harder to implement and definitely will overcomplicate the project while neither I nor anyone else need this:
+- Config option to omit some query args (if there is no `/api?key=val&abc=def` and it's allowed to omit abc, then search for `/api?key=val`)
+- Store request/response cookies in an archive
+- Config option to disable saving cookies specified by key (e.g. in case they contain credentials)
+- Config option to omit some cookies
+- Invent a custom format (or find existing) for storing query args and cookies that will make the operations listed below more handy
+
+For these usage screnarios, especially with cookies, it's simplier and overall better to self-host the web site server you are trying to archive or re-implement it in your favourite programming language and self-host.