Add a handbook page about how to get involved with porting contrib modules that Core mentors can refer people to

Today I had a short conversation with YesCT, amateescu and (later on) bojanz about if/how it would be feasible to provide help to contrib module maintainers not only in terms of documentation of the Core APIs but also for architectural decisions. In Drupal 7 we saw tons of small and huge modules alike with terrible architecture. Now that major rewrites are more or less a necessity we should try to find a way to provide friendly reviews and maybe even architectural guidance and planning before any code is writing to get those modules into a better shape without needing a full rewrite again in a second version.

It's funny that this issue came up only a few days ago. This came to my mind last night after a couple of beers at devdays and bojanz also had something similar planned for Commerce 2.x (which is why I contacted him after sharing that idea with YesCT). Documentation is obviously still greatly needed but also documentation about architectural wrong doings and common errors and pitfalls. What I have in mind goes a bit further than that though and would involve knowledgeable contributors to assist in the planning process and architectural decision making. I am not yet sure how such an effort would look but I think it could have a great impact on the quality of D8 contrib.

Starting to take a shot at this today. Will share any progress or questions in a bit.

More than a few pertinent content items already exist, starting with https://www.drupal.org/update/modules/7/8.

Evaluating next: how well they might encourage/empower someone who lands there to port 7 modules to 8. At first glance, we can probably add mention of webchick's Upgrading Your Modules.

There are 6 first-child pages within the Converting 7.x modules to 8.x parent. In addition to the parent page, there are two children with status: Incomplete. Worth noting: two of the pages in this set have been edited by HongPong in the last week, so we should coordinate with him first to see what, if any, other changes are planned.

That said, suggesting that we need to

1. verify that the substantive info is still accurate (particularly on pages last updated in 2014 or 2013
2. tighten the relational structure (consistent aliasing, re-ordering the steps, page titling)
3. make sure the content is presented in a narrative workflow, prioritizing successive to-do items/tasks, and clearly calling out supporting or alternative content as such
4. create a bridge between people with contrib modules that need to be ported and people with time and ability to help port them

I'll get us started by contacting HongPong.

I just added this as a Related issue to #1414988: [Meta/Plan] Create a new Getting Involved Guide section -- we're discussing how to restructure the Getting Involved Handbook. Anyone following this issue might want to take a look at the issue summary there and then jump down to comment #22 (everything up to comment #22 is basically/mostly in the summary).

This seems to be obsolete -- it was about converting Drupal 7 modules to Drupal 8. That documentation, as noted in comment 6, was created: https://www.drupal.org/docs/upgrading-and-converting-drupal-7-modules

We also have docs on preparing Drupal 8 projects for Drupal 9: https://www.drupal.org/docs/updating-drupal/how-to-prepare-your-drupal-7...

And Task writeups for helping out with D9/D10 readiness for contrib projects:
https://www.drupal.org/community/contributor-guide/task/create-a-drupal-...
https://www.drupal.org/community/contributor-guide/task/test-a-drupal-9-...

So I'm going to mark this as Fixed.