Consolidate Bot Opportunities Links

I have found the following:

1. https://github.com/internetarchive/openlibrary-bots/wiki/Bot-Opportunities - last updated Jun 1, 2018
2. https://github.com/internetarchive/openlibrary-client/issues/165 - last updated in 2020
3. Number 2 above is also referenced here https://github.com/internetarchive/openlibrary/wiki/Writing-Bots#bot-opportunities - last updated Mar 20, 2020

I'm not sure if we want to update the wiki to point to issue number 1 or move some of the stuff from issue number 1 to the wiki and have number 3 updated to point to the wiki.

Posting this as an issue because as a new user it's a little unclear what the process is for proposing a bot you'd like to make (or hope someone else could make). It would be a great addition to the more technical instructions described here https://github.com/internetarchive/openlibrary/wiki/Writing-Bots#applying-for-a-bot-account