create a new guide that shows how to update docs on an existing datasheet

[mattvenn]

we have this: https://docs.google.com/document/d/16YdQM4Lh3ZazVcNXhO2Ssty5hzKGp0fj3FKmcbMlFZo/edit?tab=t.0#heading=h.mcvyaz7a8clr

but I want it to be in /guides

this is in progress already

[mattvenn]

@kdotom is working on this