[Server] Added --verbose option to README

[reuank]

This option was missing in the README.
https://github.com/ggerganov/llama.cpp/blob/24ecb58168dce81646c2ed425690a106591c8c6d/examples/server/server.cpp#L2333

See also the discussion at: #7107 (comment)

[mofosyne]

Could you try adding [no ci] to your commit message as it's only just documentation changes?

https://docs.github.com/en/actions/managing-workflow-runs/skipping-workflow-runs

[reuank]

@mofosyne Like this?

[mofosyne]

Yup. Looks like it skips most CIs except for .github/workflows/server.yml for some reason, still faster than checking everything.