Sort sidebar topics in a meaningful way

I think it's confusing to talk first about pluggable transports and then circumvention. And then Onion Services...

About Tor Browser
Downloading
Installation
Running Tor Browser for the first time
Pluggable transports
Circumvention
Bridges
Managing identities
Onion Services
Secure Connections
Security Settings
Updating
Plugins
Troubleshooting
Uninstalling
Known issues
Making Tor Browser portable
Becoming a Tor Translator