Add usage example for TextCat with Dolly 2

[rmitsch]

Description

Add usage example for TextCat with Dolly 2. Authored by @kabirkhan, moved here from #180.

Corresponding documentation PR

-

Types of change

Docs enhancement.

Checklist

• I confirm that I have the right to submit this contribution under the project's MIT license.
• I ran all tests in tests and usage_examples/tests, and all new and existing tests passed. This includes
  • all external tests (i. e. pytest ran with --external)
  • all tests requiring a GPU (i. e. pytest ran with --gpu)
• My changes don't require a change to the documentation, or if they do, I've added all required information.

[rmitsch]

The failure is to due the MacOS/Pydantic stuff that will be fixed (well, worked around) once we merge #180 into develop and update this branch.

[svlandeg]

Looks good, thanks!