Add instructions on how to validate with Mustang

diff --git a/README.rst b/README.rst
index 50e00d1a99ac6178283817ab352a9fd0c9a92f21..4666ec513e033f08fcb67bce38a7984a3876b2b0 100644 (file)
--- a/README.rst
+++ b/README.rst
@@ -122,6 +122,14 @@ To automatically sort your Imports as required by CI::
     pip install isort
     isort -rc .
 
+To validate files using mustang::
+
+    git clone https://github.com/ZUGFeRD/mustangproject.git
+    cd mustangproject
+    git checkout core-2.5.1
+    ./mvnw clean package
+    java -jar Mustang-CLI/target/Mustang-CLI-2.5.1-SNAPSHOT.jar --action validate --source invoice.pdf
+
 
 Credits and License
 -------------------