[Inference Providers] Rework the Get started page (#1806)

* wip: rework inference providers getting started

* fix open tag?

* test?

* test

* get rid of nested hfoptions

* reorganize sections a bit

* typo fix

* (vibe-coded) wording pass

* text-to-image section

* (vibe-coded) more comprehensive documentation

* remove TODOs

* (vibe-coded) blurb llm

* cohanges from code review

* clarify some woridng

* more

* fix typo

Author: SBrandeis