Add updated documentation

[mcallic2]

Summary

Adds comprehensive documentation for the community release: a full User's Guide, a quick-start root README, and supporting reference/example assets. Replaces the outdated docs/README.md.

Changes

• README.md (new, root) — Quick-start guide with condensed setup/run steps for both RDHPC and non-RDHPC users, sample track plot output, and links to the full User's Guide
• docs/UserGuide.md (new) — Comprehensive User's Guide covering introduction, repository structure, getting started, installation and building (RDHPC, Spack, manual, and containerized methods), configuring and running the tracker, output files, troubleshooting, and additional resources
• docs/README.md (removed) — Outdated documentation superseded by docs/UserGuide.md
• compile/compiletrkr.sh — Removes the container and personal options from the script's help text, since these are not yet functional and were misleadingly listed as available; they're planned for a future release
• compile/src_code/images/ → docs/images/ — Moved radiidoc_figure1.png and radiidoc_figure2.png to sit alongside the rest of the documentation assets
• docs/images/track_plot_examples/ (new) — Example tropical cyclone track plot images (individual plots + composite gallery) referenced in the root README's "Sample Output" section
• run/init_data/example_file.txt (new content) — Documents the required fixed-width column formatting for init_data/ config files (leadtimes.txt, hgt_levs.txt, tmp_levs.txt, vortex_tilt_levs.txt, vortex_tilt_vars.txt)

Notes

• Non-RDHPC installation guidance (Spack, manual, container) is documented as a starting point; comprehensive step-by-step instructions for these paths are still in progress and will be expanded in a future update.