Normalise on 'Rockstor' capitalization #2916

[phillxnet]

User visible text update to newer capitalisation.
I.e. "RockStor" -> "Rockstor".

Fixes #2916

[phillxnet]

Testing

An rpm was successfully build from this PR's branch, X86_64 Leap 15.6 host, and the associated services started. The following are screen grabs from the most prominent changes here:

Initial Web-UI setup page

Create new user page

Appliances page

[phillxnet]

@FroggyFlox & @Hooverdan96 moving to merge as all changes here are simply cosmetic. We have a minor re-wording but nothing too major and in-line with the cosmetics frame re grammar correction.

I included the associated issue in our current Milestone of 'next stable' to avoid apparent typo aspersions :) and to add a little polish for our next Stable release.

N.B. this PR modifies lines close to those associated with the pending issue #2920 by @Hooverdan96.