re-add developting section

README.md

@@ -90,6 +90,25 @@ Anyone is welcome to contribute and help out. However, hate, discrimination and
 
 If you want to add more translations, see our [weblate-project](https://hosted.weblate.org/projects/round-sync/round-sync/)!
 
+## Developing
+
+You should first make sure you have:
+
+- Go 1.20+ installed and in your PATH
+- Java installed and in your PATH
+- Android SDK command-line tools installed OR the NDK version specified in `gradle.properties`
+  installed
+
+You can then build the app normally from Android Studio or from CLI by running:
+
+```sh
+# Debug build
+./gradlew assembleOssDebug
+
+# or release build
+./gradlew assembleOssRelease
+```
+
 
 ## License
 This app is released under the terms of the [GPLv3 license](https://github.com/newhinton/extract/blob/master/LICENSE). Community contributions are licensed under the MIT license, and [CLA Assistant](https://cla-assistant.io/) will ask you to confirm [a CLA stating that](https://gist.githubusercontent.com/x0b/889f037d76706fc9e3ab8ee1c047841b/raw/67c028b19e33111428904558cfda0c01039d1574/rcloneExplorer-cla-202001) if create a PR.