Create better guides for onboarding and add it to BrowserOS README.md

[felarof99]

We already have good guide to setup and use ollama, need to add it to Github.

https://browseros.notion.site/Local-Models-Guide-22d77fbf91b9809ab28fdcfd43d86760

[anujchoudhary-17]

Would love to contribute on this, as I have done the setup for Windows, and can also list the issues I encountered!