Streamline sdk documentation

Problem

Four different documents for an overview of our SDKs

Ory Hydra has a sdk.md with overview of all SDKs
Ory Keto has a folder sdk with index.md with overview of all SDKs
Ory Kratos has no document like this, instead its moved to "start-building/other-languages.md" in the Cloud documentation.

Solution I would like

[ ] Rename Keto SDk document and move dir up.
[ ] Rename start-building/other-languages.mdx to /sdk.mdx (<- this will be main sdk overview page for Ory Cloud) Since Kratos is now using the same SDK as Ory Cloud we can also link this document in the Kratos selfhosted docs. Tweak the first sentence, so it works for both.

Alternatives

nothing immediately came to mind, but open for ideas.

ory / docs