Update README with steps to create a windows exe

README.md

@@ -5,10 +5,20 @@ Replaces file usage globally in the Wikimedia Wikifarm.
 This java program requires a minimum version of Java 8 installed. Consult [the wiki page](https://commons.wikimedia.org/wiki/Commons:GlobalReplace) for further instructions.
 
 ## Compile
+### Jar
 [Download the precompiled jar file](https://github.com/Commonists/GlobalReplace/releases) or build it yourself after downloading the source with a simple
 
 ```
 ant
 ```
 
 You need [Apache Ant](http://ant.apache.org) installed.
+
+### Windows exe
+To also build the windows exe:
+
+```
+ant dist
+```
+
+You need to download launch4j into the folder `./launch4j`.