Update 'README.md'

README.md

@@ -1,2 +1,9 @@
 # gitness
 
+```
+docker run \
+  -p 3000:3000 \
+  -v /var/run/docker.sock:/var/run/docker.sock \
+  -v /tmp/gitness:/data \
+  harness/gitness
+```