Update README

Author: marcprux

README.md

@@ -1,2 +1,18 @@
 # swift-test
+
 GitHub action to build and run Swift package tests on an Android emulator
+
+You can add this action to your Swift CI workflow from the
+[GitHub Marketplace](https://github.com/marketplace/actions/swift-android-action).
+
+## Releasing
+
+To create a new release, make a new tag (like 1.0.0),
+and then update the symbolic major v1 tag with:
+
+```
+git tag -fa v1 -m "Update v1 tag"
+git push origin v1 --force
+```
+
+