Add initial onboarding notes

[Mark-Simulacrum]

The lack of this came up in discussion during an all-hands session as a missing artifact. I'm not sure whether this should be in the Forge (but where else?) but seems like an OK starting point. Also probably much more than just this would be helpful.

cc @rust-lang/leadership-council @carols10cents @JakobDegen @rylev @scottmcm @spastorino

Rendered

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[spastorino]

What's the idea or plan here? what was the all hands session about? can we link the discussion?.
I guess the idea would be that we would provide more onboarding docs for the different parts of the project later?.

[rylev]

I personally know of two places where improving onboarding was actively was discussed:

• Session on burnout
• Session on Project and Foundation relations

[Mark-Simulacrum]

Thanks Ryan! Yes, this is coming out of the Foundation discussion for me (I didn't get a chance to attend the other session).

My primary goal is to get something landed here, and it can be extended over time. I'm not sure whether this is the best form for it, but it seems like a reasonable-ish starting point and is net-new content as far as I know.