Add minimum storage requirement on internet connected instance where mirroring is run

[dmc5179]

Add minimum storage requirement on internet connected instance where mirroring is run. Mirroring of the cluster images is about 10GBs, adding in the redhat-operators is over 100GBs, adding in the certified and/or community operators is much larger.

[usrbinkat]

Basic storage requirements are listed HERE additional payload capacity planning is currently expected to be handled by the user.

PR's are welcome if you have a proposal how to improve the messaging for this, otherwise I will close this bug for now.