Creates the new Support Time Off page

Why is this change being made?

There is no existing documented guidance within the Support Team to help people to take time off from work in a way that both makes the time off successful (happy, fun, productive, effective, and so on) and prevents problems for the rest of the team or our customers. This new page in the Support Team Handbook offers that guidance.

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][transparency]
• Assign this change to the correct DRI
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to your manager.
  • 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][mr-buddies-slack].
  • 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.