readme : add option, update default value, fix formatting

[pothitos]

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Thanks for the awesome project 🙏

PR title summarizes these three commits for documentation.

[mofosyne]

FYI for other reviewers https://github.com/ggerganov/llama.cpp/pull/10271/files?w=1 for no whitespace diff.

[pothitos]

Thanks for the tip, Brian! I've added another commit to address Markdown formatting issues.

Here’s an overview of the five commits included in this PR.

1. Introduces --no-display-prompt argument in the documentation.
2. Fixes the default --ctx-size value in the documentation.
   • This can be verified with llama-cli --help | grep ctx-size
   • The correct value is already present in the server documentation https://github.com/ggerganov/llama.cpp/blob/ce2e59ba107cf71ed566040ff20a15d1c58e09c2/examples/server/README.md?plain=1#L42
3. Corrects formatting issues in the server documentation caused by extra spaces.
   • You can compare the original documentation here and the updated version here.
4. and 5. adjust indentation of commands inside lists for better readability.

[pothitos]

Hello! The reason for force-pushing is to address "This branch has conflicts that must be resolved" messages and ensure the branch is up-to-date while it's still pending merge. Let me know if there's anything else needed!