Improve tegon documentation - self-hosting.

[AggManik]

Current self-hosting documentation is slightly outdated and miss some steps.
Link - https://docs.tegon.ai/oss/self-deployment

[smultar]

The documentation for sure needs some work. We also need a list of things that are currently planned, working and bugged.

[chidam333]

I got the gist on how to run it today. When I read the instructions again now I feel it's too complicated.
Steps can be
Clone the docker repo
Edit env variables
Run docker compose up
The startup script seems weird. Clone docker repo again but why ? We get the startup script by cloning the docker repo at the first place right?
also the versions can all be present in env and commented out as required