Investigate unique sidenavs for "Why cloud.gov" vs "Documentation"

[cmajel]

Currently, when I select an item under "Why cloud.gov," I see the full sidenav for all the Documentation pages.

What I see when I click "Why Cloud.gov > We're FedRamp Authorized

This creates one large sidenav for a number of diverse topics, which can be harder to navigate. Having unique sidenavs for "Why Cloud.gov" vs "Documentation" could create simpler, more thematic side navigation that are easier to navigate and remove distractions.

Note that this relates to the ongoing content audit that the Cloud.gov team is working through (#1545).

Done when:

• [ ] Future team to fill in