Update README.md

README.md

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 [![CI](https://github.com/spenserblack/gh-collab-montage/actions/workflows/ci.yml/badge.svg)](https://github.com/spenserblack/gh-collab-montage/actions/workflows/ci.yml)
 [![codecov](https://codecov.io/gh/spenserblack/gh-collab-montage/graph/badge.svg?token=jhBJJl4oQ2)](https://codecov.io/gh/spenserblack/gh-collab-montage)
 
-Combine avatars of all collaborators into one image
+Combine avatars of all collaborators into one image. Just call `gh collab-montage` and this extension will query all contributors, fetch their avatars, and
+combine them all into one PNG. This extension also provides a public library to provide utilities for making your own montage.
+
+## Credits
+
+This extension was inspired by [avatar-montage](https://github.com/benbalter/avatar-montage).