Update README.md with newer field names for API.

[roarinpenguin]

In the env file there are several fields for API Keys:

API keys (only used if DISABLE_AUTH=false)

API_KEYS_ADMIN=
API_KEYS_READ_ONLY=
API_KEYS_WRITE=

Integrations

S1_SDL_API_TOKEN=

The documentation file (https://github.com/natesmalley/jarvis_coding?tab=readme-ov-file#authentication-settings) reports different content and this can be confusing.

[HermessNRJ]

Hello, I just made a PR that improves the documentation and configuration section in .env #37