Add ":Z" options to volume mounts

Gives read-write access to the volumes. See https://web.archive.org/web/20190728100417/https://www.projectatomic.io/blog/2015/06/using-volumes-with-docker-can-cause-problems-with-selinux/

readme.md

@@ -359,7 +359,7 @@ Patching the font of your own choosing:
 
 * Use docker
   ```
-  docker run --rm -v /path/to/fonts:/in -v /path/for/output:/out nerdfonts/patcher [OPTIONS]
+  docker run --rm -v /path/to/fonts:/in:Z -v /path/for/output:/out:Z nerdfonts/patcher [OPTIONS]
   ```
 
 Full options: