docs(upgrade): added information about faster upgrade

docs/source/install/upgrade.rst

@@ -15,7 +15,7 b' Then upgrade each stack based on instructions provided from the help output:'
 
 .. code-block:: bash
 
-    ./rcstack stack-upgrade
+    ./rcstack stack-upgrade <STACK_NAME>
 
 
 .. note::
@@ -24,6 +24,19 b' Then upgrade each stack based on instructions provided from the help output:'
     This will spawn 2x more nodes to perform the upgrade and then remove the old instances. This way all incoming traffic
     will be handled continuously without any interruptions on upgrade
 
+The above upgrade uses default timeouts to wait for any currently ongoing traffic to stop to kill the workers.
+There are two additional flags that can be used for a faster upgrade that could let to end users errors, or small downtime
+but will enforce the upgrade to be performed as fast as possible.
+
+
+Fast upgrade with max 30s wait time after new upgraded containers start, and wait 5s before force killing old
+containers
+
+
+.. code-block:: bash
+
+    ./rcstack stack-upgrade rhodecode --stop-wait 30 --docker-stop-wait 5
+
 
 
 Install specific version