Rename "Add a new XY" steps

Based on the poll results, here are the most upvoted new names for steps

From:

* Add a new connection of type "bridge" named "bridge0" for device "bridge0" and options "opts"
* Add a new interface of type "dummy" named "dummy0"
* Add a new network namespace named "ns1"

To:

* Add "bridge" connection named "bridge0" for device "bridge0" with options "opts"
* Create "dummy" device named "dummy0"
* Add namespace "ns1" with options "opts"