[enhancement]: Add standard CLI features to rapid2 command

[riverma]

What would you like to suggest?

The rapid2 command-line program is missing several standard CLI features that users expect from modern command-line tools.

Missing Standard CLI Features:

1. --version / -V flag - No way to check the installed version
2. Citation info - Not displayed when running without arguments or in help output (users should know how to cite RAPID2)
3. Examples section - No usage examples in help text
4. Descriptive help text - Current description ("This is RAPID2") is too minimal
5. Exit codes documentation - Not documented (if used)

Minimal Recommendations to Implement:

1. Add --version flag

   • Example: parser.add_argument('--version', action='version', version='%(prog)s 2.0.0')

2. Improve program description

   • Current: "This is RAPID2"
   • Suggested: "RAPID2: Routing Application for Python Integration of Discharge - River routing model for streamflow computation"

3. Add epilog with usage example and citation info

   • Show basic command example at bottom of help text
   • Include reference to CITATION.cff for proper citation

[riverma]

Feedback: lets bunt on the --version flag for now until we identify a ideal versioning scheme.