Cleaning up examples/ models and starter .env files (#1124)

Closes https://github.com/go-skynet/LocalAI/issues/1066 and
https://github.com/go-skynet/LocalAI/issues/1065

Standardizes all `examples/`:
- Models in one place (other than `rwkv`, which was one-offy)
- Env files as `.env.example` with `cp`
    - Also standardizes comments and links docs

examples/langchain-chroma/models/embeddings.yaml

@@ -1,6 +0,0 @@
-name: text-embedding-ada-002
-parameters:
-  model: bert
-threads: 4
-backend: bert-embeddings
-embeddings: true