chore: added oel configuration schemas

[deepakprabhakara]

Related Issue or Design Document

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Further comments

[deepakprabhakara]

We still need to figure out a way to automate the version of the spec being read.

[vinckr]

love it, afaict everything renders well

I found some inconsistencies where the self-hosted config reference is found in the sidebar, but I don't think we need to address it in this PR.
also the OEL sidebar needs some structure down the line, but again doesn't need to be in this PR.

lgtm