docs: Add development overview and documentation resources
- [x ] This change is worth documenting at https://docs.all-hands.dev/
- [ x] Include this change in the Release Notes. If checked, you must provide an end-user friendly description for your change below
End-user friendly description of the problem this fixes or functionality that this introduces. This adds a Development Overview Page to the User Guide documentation. Since most of this is documented in the Git Repository and we don't want to maintain a lot of separate documentation, it acts as a guide with Reference Documents to git.
Give a summary of what the PR does, explaining any non-trivial design decisions. Primary decision was to keep the repo as the Core Developer Documentation, and treat this as a quick reference for Developers to look up specific items. Might be good to add an FAQ at a future date. http://localhost:50374/modules/usage/how-to/development-overview
Link of any specific issues this addresses.