Update Digital Experience sprint process

Why is this change being made?

I had a few questions about the sprint process and used this MR to clear them up. We've updated the sprint planning/release/retro docs, added the Digital Experience YouTube playlist link specifically in our process section, moved some of the weighting language around, and identified a separate issue to update the calendar shared in this page.

We also added links to the issue boards created by @brandon_lyon. I think this is a good MVC to clear up some of the new process changes, and we should take additional issues elsewhere.

Author Checklist

• Provided a concise title for the MR
• Added a description to this MR explaining the reasons for the proposed change, per say-why-not-just-what
• Assign this change to the correct DRI

added 1 commit

• 0f4f4840 - fix some small typos

Compare with previous version

assigned to @tywilliams

requested review from @mpreuss22

Some of the things I found to be great discussion on slack:

Can someone clarify something. Milestones are pre-set correct, Fri: Feb xx,xxx ? Does the Friday represent the day the work will begin? Or does the Friday label represent the week that has ended?

my opinion: following agile theory, we should make promises do deliver something by the END of an ITERATION. it’s up to us to figure out how to organize and do that, but it doesn’t make sense to me to use ITERATIONS at all if we have deliverables in the middle of it

mentioned in issue #9810 (closed)

resolved all threads

added 3578 commits

• 0f4f4840...a1c69dfb - 3577 commits from branch master
• c68e2d5c - Merge branch 'master' into 'tw-digital-experience-process-update'

Compare with previous version

resolved all threads

resolved all threads

mentioned in issue #10986 (closed)

added 1 commit

• aa9d17f6 - wrap up items from MR discussion, other than updated calendar

Compare with previous version

marked this merge request as ready

changed the description

unassigned @mpreuss22