Document the CLI in docs/CLI.md

[NovaCode37]

The CLI is documented by one bullet in the README:

run scans headlessly via python cli.py scan example.com --json, manage scheduled re-scans with python cli.py watchlist add ..., and see which modules -m accepts ... with python cli.py modules

Everything else lives only in --help: the output formats (--json, --html, --pdf, --graphml, --gexf), -m and how it is validated against the target type, --verbose and --quiet, the watchlist subcommands, and what prism modules --type prints. Someone deciding whether to script PRISM has to install it first to find out.

What to do:

• Add docs/CLI.md with one section per command (scan, modules, watchlist), each with a real example and its output trimmed to a few lines.
• Cover exit codes for scan, and what happens when a module is skipped for a missing key (the module still appears in --json with status: skipped).
• Link it from the README bullet and from docs/CONFIGURATION.md.

Use python cli.py <command> --help as the source of truth, and run each example so the output is real rather than invented.

Done when every flag --help lists for the three commands appears in docs/CLI.md with at least one example.

[AartiKandpal]

Hi! I would like to work on this issue for Hacktoberfest. Please assign it to me.