Create docs-decision-tree.md

[shannonbux]

Will be accepting comments, discussion, and feedback until October 31st!

[calcsam]

Awesome! Here are some screenshots of the Whimsical chart for reference:

[marcysutton]

Any feedback from Hacktoberfest now that it's been over for a while?

[shannonbux]

I would say the things that went well:

• the code-owners @gatsbyjs/docs team did a great job gathering all docs-related issues into one spot since it tagged the team automatically for anything in /docs/ /tutorial/ or 'doc-links.yml' or 'tutorial-links.yml'
• The OSS team has done a good job merging things that don't need my specialization - for example, without waiting for docs team approval, they merge stuff that makes docs more accurate, more up-to-date, more in line with the style guide. I like this. Don't know if they like it...:)

The things that are still remaining issues imo:

• I don't know how to change code owners notifications and don't know who owns it or how to look at it, so I'm not sure if my request that I only be notified about changes to 'doc-links.yml' and 'tutorial-links.yml' instead of all docs changes has been accomplished
• I also wanted to be notified about any docs being deleted or added to /docs/, not sure if it's possible to automate this.
• Sometimes, really big changes to the docs need a technical review after I do a docs review, and I don't know who to assign or ping.