Guidance for external contributors on how to get large contributions into OpenSSL

[mattcaswell]

From the OTC meeting minutes (otc/meeting-minutes/2023/minutes-2023-08-22.txt)

AI: Matt to write a first draft of a guide for feature contributors

[nicowilliams]

Sometimes a contributor might start a contribution, run out of steam, and come back a year later when the upstream has merged a few thousand commits and some number of those cause conflicts for the contributor. There are tools meant to help with this, as git rebase and git merge can both be a nightmare in such cases. I linked four useful tools for this in a comment on #73.

I recommend picking and recommending one of these, though also listing the others (they all do roughly the same sort of find-and-rebase-onto-the-oldest-conflict-causing-upstream-commit-then-repeat-from-there thing).

[mattcaswell]

Thanks @nicowilliams - I'll take a look.

[arapov]

from: #347

Write up some of the work practices I pioneered when developing QUIC MVP for 3.2
Compare with the project's historical work practices
Ideally talk to some of the others before I do this to understand historical work practices and the context of how I approached QUIC MVP