Add instructions for developing the app

DEVELOPMENT.md

@@ -0,0 +1,39 @@
+# Developing Gitnuro
+
+## Installing libssh
+
+Gitnuro depends on libssh being present as an external, native library (using [JNA](https://github.com/java-native-access/jna)).
+While the release GitHub workflow packages it automatically, you'll need to install it manually when developing locally,
+such that it's available on the `$PATH`. See [here](https://www.libssh.org/get-it/) for one-liner installation
+instructions with your OS's package manager, or manually download a binary or compile it from source and place it in the
+main project directory (next to `LICENSE`) or elsewhere on your `$PATH`.
+
+## Setting up an IDE
+
+If you don't have another preference, the recommendation is to download and install
+[IntelliJ IDEA Community Edition](https://www.jetbrains.com/idea/download/)
+(possibly through the JetBrains Toolbox, if you have it already) as well as the
+[Compose Multiplatform IDE Support](https://plugins.jetbrains.com/plugin/16541-compose-multiplatform-ide-support)
+plugin.
+
+## Alternative: Setting up JDK for use on CLI
+
+You don't need this if you only use the JDK installed by IntelliJ IDEA.
+
+Check which Java version this project currently uses (`cat build.gradle.kts | grep JavaLanguageVersion`) and install it.
+For instance on Debian-based systems, you'd run:
+```bash
+sudo apt-get install openjdk-17-jre openjdk-17-jdk libssh-dev
+export JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64
+```
+Once it works (e.g. `./gradlew build`), you may want to add that latter line to your `/etc/environment`.
+
+## Running the app / unit tests
+
+From the "Gradle" window in the IDE, under "Tasks" select "compose desktop > run" or "verification > test"
+for the main app or unit tests, respectively, and run it.
+Next time, it will already be in the "Run Configurations" at the top right of the IDE, so you
+won't have to open the "Gradle" window again.
+You can also run these in debug mode and set break points in the code.
+
+Alternatively on CLI: `./gradlew run` or `./gradlew test`.

README.md

@@ -76,6 +76,7 @@ Gitnuro has support for the following features:
 If you find a bug or you would like to suggest a new feature, feel free to open an issue.
 
 Pull requests are also welcome but please create an issue first if it's a new feature. If you want to work on an existing issue, please comment so I'm aware of it and discuss the changes if required.
+See [this page](DEVELOPMENT.md) for how to set up your development environment.
 
 ## FAQ