Changes to cycle analytics docs

@mksionek - just double checking, but I haven't seen any changes to the current docs for moving cycle analytics to the analytics nav and moving it to group level?

@eread: we are making the following changes to cycle analytics during 12.2:

• moving to group level under a new nav bar - can be added on the existing cycle analytics page, but I wonder whether we should have an additional MR for the fact that we are setting up a new analytics space? (@johnjeremiah - do you think this is something that should go in a release post as well? )
• adding a scatterplot - can be added on the existing cycle analytics page (cc: @ahegyi & @blabuschagne), no need for a release post @johnjeremiah?
• adding customizable stages (this might slip to 12.3). I think for the customizable stages we should probably have a separate MR since it might not go in 12.2.(cc: @ekigbo & @ahegyi) (@johnjeremiah - I will be preparing a release post for this so it's ready)