Add "virtual environments" section in navigation bar

Describe the change

I propose to move these pages from the navigation section "Developer documentation" to a new section above called "Virtual Environments":

• Virtual environments: Servers
• Virtual environments: Admin Workstation
• Virtual environments: Using Qubes
• Portable SecureDrop Demo

Eventually the page files could be moved to a separate folder like "venvs" but, what's important to me is to have a separate section like this:

How will this impact users?

1. I think that a less crowded "Developer documentation" section would be beneficial for everyone
2. New administrators won't have to look through all the documentation before finding what they need to have a virtualized environment for evaluation purposes. At the same time developers won't have any difficulty in finding what they need even if it's not in "their" section. Win-win

User Research Evidence

I'm new to Securedrop at it was hard for me to navigate the documentation. Only after two days with my nose in the documentation I realized that a portable setup is described: I simply couldn't see it.

Additional context

Start by locating the navigation configuration for the "Developer documentation" section and the four listed pages. Move those pages into a separate "Virtual Environments" section above it, then verify that the navigation is less crowded and all four pages remain easy to find.