Reduce/consolidate duplicated and outdated content in the product handbook
Upon completed issue www-gitlab-com#11014 (closed), so we're clear on what is priority for PM's job, let's go through the product handbook to align/focus it to support, by seeing what content can be:
- removed / consolidated
- made more brief/consumable-- sometimes this could be a simple rewrite, sometimes this could be introducing video content
Edited by Farnoosh Seifoddini