contributing: add v1 branch

Author: tmorrell

CONTRIBUTING.md

@@ -12,7 +12,7 @@ Everyone is asked to read and respect the [code of conduct](CODE_OF_CONDUCT.md)
 
 A quick way to find out what is currently in the near-term plans for this project is to look at the [GitHub issue tracker](https://github.com/caltechlibrary/iga/issues), but the possibilities are not limited to what you see there – if you have ideas for new features and enhancements, please feel free to write them up as a new issue or contact the developers directly!
 
-New development takes place in the `develop` branch. We try to make the `main` branch reflect the latest release, meaning that what you see in the main branch reflects what you get with the lateset released version of the software.
+New development takes place in the `develop` branch. The `v1` branch reflect the latest release, so that code should be the same as the lateset released version of the software.
 
 
 ## Submitting contributions