Consolidate health check endpoints in documentation

[wxsms]

These endpoins looks like are performaning same behaviour now.

@app.get("/health")
@app.get("/health_generate")
async def health_generate(request: Request) -> Response:
    """
    Check the health of the inference server by sending a special request to generate one token.

    If the server is running something, this request will be ignored, so it creates zero overhead.
    If the server is not running anything, this request will be run, so we know whether the server is healthy.
    """