add Sambanova to the list of LLM providers in the documentation

[wlauppe]

Hello, the fastest Provider of the Deepseek-R1 Model is currently. Sambanova
Speed is about 5 times as fast as the other providers. I really recommend to try it.

That is the config i got sambanova working with

(gptel-make-openai "Sambanova" ;Any name you want
  :host "api.sambanova.ai"
  :endpoint "/v1/chat/completions"
  :key gptel-api-key
  :stream t
  :models '(DeepSeek-R1))

together with the

machine api.sambanova.ai login apikey password xxxxxxxxxx 

liine in ~/.authinfo

I think it makes sense to include this in the documentation.

Link to the company:
https://sambanova.ai/

[karthink]

Sure, please raise a PR adding this to the README.