There’s no automated submission process like maven/jcenter. Just use the
Contact option and submit details of your library.
I’d also recommend submitting to Android Weekly which features new libraries. Just submit your repo link at the bottom of the page here
I’ve submitted libraries to both via these methods and they do get picked up.
You can also consider adding your libs to the new “Awesome Android” list. It’s the new kind on the block https://android.libhunt.com/contribute