Summary

• Add a review-branch skill for running Greptile CLI reviews on the current local Git branch before opening a PR/MR.
• Document Greptile CLI setup, review commands, output formats, and relevant flags.
• Update README install and usage instructions for the new skill.

Why

check-pr and greploop cover workflows after a PR/MR/CL review target exists. This adds a pre-PR workflow for committed local branch diffs using greptile review.

Notes

• Uses Greptile CLI instead of PR/MR comment triggers, dashboard review flows, or app-based review triggers.
• States that Greptile CLI reviews committed branch changes and ignores uncommitted changes.
• Does not create PRs/MRs by itself; it hands off to the user's normal PR/MR creation workflow when requested.