Add triaging document

[mx-psi]

It would be great to have a triaging document of some kind describing the areas that issues can fall into and what the process is.

I am going to start by keeping a list of issues without a clear area here so that we figured out the patterns. Feel free to edit this issue list if you find other examples

Calendar management

• #2678

Misc issues without a clear area

• #2679
• #2729

Github

• #2802
• #2793
• #2769
• #2765
• #2763
• #2872