build: set the release version to v1.19.4

For the patch release update the docs and images to
v1.19.4

Signed-off-by: Michael Adam <obnox@samba.org>

Documentation/Storage-Configuration/Monitoring/ceph-monitoring.md

@@ -48,7 +48,7 @@ There are two sources for metrics collection:
 From the root of your locally cloned Rook repo, go the monitoring directory:
 
 ```console
-$ git clone --single-branch --branch v1.19.3 https://github.com/rook/rook.git
+$ git clone --single-branch --branch v1.19.4 https://github.com/rook/rook.git
 cd rook/deploy/examples/monitoring
 ```