Use direct language on distribution information page

Why is this change being made?

The page had links to source code repositories for CE and EE, and was using language that was not focusing on the state as found today. By referencing what the single source of truth is for source code for GitLab Rails, and making history less prominent I hope to get some additional clarity for people reading the page.

Does this MR meet the acceptance criteria?

Assign to DRI

• Did you assign this change to the correct DRI of the page or information you are changing?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what