Update README.md

Author: ethanjli

README.md

@@ -1,3 +1,5 @@
 # openuc2.github.io
 
 This repo redirects end-users from legacy documentation URLs at `openuc2.github.io` to `docs.openuc2.com`, which is deployed from the [openUC2/docs-prod](https://github.com/openUC2/docs-prod) repo.
+
+This is needed because the `openUC2/openuc2.github.io` repo used to be a deployment of the master branch of the docs site, so that `openuc2.github.io` would redirect to <https://docs-dev.openuc2.com> - which is undesirable for customers opening QR code sending them to `openuc2.github.io`.