Add L2 comparisons to "comparisons" page

[Bill Laboon]

We should add L2 comparisons to the Comparisons section of the wiki (maybe not specific ones, but at least comparing parachains to optimistic and ZK rollups)

Shawn T. already put together a decent overview in this slide deck.

[Filippo]

hey @laboon did you check if what has been done here --> #3789 does not satisfy your request? The PR has been open for a while, I sent you a review request

[bader y]

Addressed and merged here: #4747