Incorrect instructions for building from source

The [Building from Source](https://docs.jabref.org/installation#building-from-source) instructions say to type the following:
```
git clone --recurse-submodules --depth=10 https://github.com/JabRef/jabref
cd jabref
./gradlew assemble
./gradlew jlink
```

The `gradlew jlink` task does not exist in [jabref/build.gradle.kts](https://github.com/JabRef/jabref/blob/main/build.gradle.kts).
