Create onboarding doc for the content team

[dorothyyeager]

User story
As a new member of the content team, I need to get up to speed on what I need to know.

To do

• Create an onboarding document for the content team. This could include the Wagtail instructions Info Division drafted, the content guide (Update and expand content style guide #1174), as well as other documents on team processes, instructions, etc.
• Add info to team onboarding materials and wikis.

[dorothyyeager]

I've begun working on this document and hope to have @AmyKort look it over later this week.

[dorothyyeager]

Have sent the document to @AmyKort and @rhoughfec to look over to ensure I didn't miss anything.

[dorothyyeager]

Content team has reviewed the onboarding docs and we're ready to onboard our new member!
Content onboarding document: https://docs.google.com/document/d/13vzH694_0ksQUtO3QsBunIOfI6hMn4Qj_aSqi_fAeBg/edit?usp=sharing
We've also added relevant content to the overall onboarding document at https://docs.google.com/document/d/18ZjPvNrdW3wn9pUx7hSNbaMlaEaPPOGzOHh-WjLiVOg/edit?usp=sharing and to the team's wiki.
Work completed and ready to close.