README: Fix link to "starter" issues

Was linked to unused tag. Changed link to "good first issue" tagged issues.

Signed-off-by: Josh Richards <josh.t.richards@gmail.com>

README.md

@@ -38,7 +38,7 @@ More information on how to contribute: <https://nextcloud.com/contribute/>
 ## Start contributing :hammer\_and\_wrench:
 
 Make sure you read [SETUP.md](https://github.com/nextcloud/android/blob/master/SETUP.md) and [CONTRIBUTING.md](https://github.com/nextcloud/android/blob/master/CONTRIBUTING.md) before you start working on this project. But basically: fork this repository and contribute back using pull requests to the master branch.
-Easy starting points are also reviewing [pull requests](https://github.com/nextcloud/android/pulls) and working on [starter issues](https://github.com/nextcloud/android/issues?q=is%3Aopen+is%3Aissue+label%3A%22starter+issue%22).
+Easy starting points are also reviewing [pull requests](https://github.com/nextcloud/android/pulls) and working on [starter issues](https://github.com/nextcloud/android/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22).
 
 ### Getting debug info via logcat :mag: