Don't use cellar to illustreate provisioning commands (feature:*) in documentation

In the provisioning section of the Karaf User Guide, it is preferable to use a smaller, less significant feature than "cellar" to illustrate the feature:* provisioning commands, as users probably won't want to load such a significant feature by accident.

[1] https://github.com/apache/karaf/blob/master/manual/src/main/asciidoc/user-guide/provisioning.adoc