README: Document the Nix setup

README.md

@@ -2,7 +2,18 @@
 TrueDiffDetective extends [DiffDetective](https://github.com/VariantSync/DiffDetective) by the option to chose [truediff](https://gitlab.rlp.net/plmz/truediff) as diffing algorithm.
 It is (mainly) implemented in Scala and using sbt as build tool (like truediff), but can easily be used in Java/Maven projects as well.
 
-## Setup
+## Nix Setup
+You can obtain a local maven repository with TrueDiffDetective and all necessary
+dependencies by running `nix-build -A maven`. It can be used by passing
+`-Dmaven.repo.local=result` to `sbt` or `mvn`.
+
+Alternatively, the plain TrueDiffDetective jars can be build by running
+`nix-build`. The jar can be installed into your Maven cache using something like
+```bash
+mvn install:install-file -DgroupId=org.variantsync -DartifactId=TrueDiffDetective -Dversion=0.1.0-SNAPSHOT -Dpackaging=jar -Dfile=./result/share/java/truediffdetective_2.13-0.1.0-SNAPSHOT-javadoc.jar
+```
+
+## Manual Setup
 ### Requirements and Dependencies
 - Scala 2 and sbt (Scala 3 will only work with some modifications)
 - Java 17 and Maven (for DiffDetective)
@@ -36,7 +47,7 @@ To install truediff using sbt:
     sbt publishM2
 ```
 
-### Using TrueDiffDetective
+## Using TrueDiffDetective
 To use TrueDiffDetective in a sbt project add dependency:
 ```
     "org.variantsync" % "truediffdetective_2.13" % "0.1.0-SNAPSHOT"