WIP - 2020 Memory Group Recap

Why is this change being made?

This is a new page being added to the Memory Group section under Enablement in the handbook https://about.gitlab.com/handbook/engineering/development/enablement/memory/

This page is to highlight all of the great work done by the Memory Group in our first full year as a team. The goal is to provide a quick overview for each accomplishment along with links to the relevant epics or issues. Often the descriptions are a direct copy from those issues or epics (no need to repeat work). Additionally there is a quick Impact summary for each accomplishment.

Each section, ideally, will have an overview with links to descriptions and an impact summary with links to detailed descriptions of the impact.

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
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the "Maintained by" section in on the page being edited.
  • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in #mr-buddies.
  • If the changes relate to any part of the project other than updates to content and/or data files please make sure to ping @gl-static-site-editor in a comment for a review and merge. For example changes to .gitlab-ci.yml, JavaScript/CSS/Ruby code or the layout files. (this requirement has been removed pending identification of a new DRI for the handbook)