[Bug 1136030] New: Need a new chapter about upgrading Fedora

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1136030

Bug ID: 1136030
           Summary: Need a new chapter about upgrading Fedora
           Product: Fedora Documentation
           Version: devel
         Component: install-guide
          Assignee: [e-mail]
          Reporter: [e-mail]
        QA Contact: [e-mail]
                CC: [e-mail], [e-mail]

The current upgrade chapter is pretty much completely useless. We need a new
one that would cover:
* Automatic upgrades with FedUp, including how to prepare and how to clean up
after the update finishes
* Manual upgrade (or reinstall) - manually booting the installer on an existing
system and using the normal installation process to overwrite the root
filesystem while keeping the rest of the system (/home and any other separate
filesystems) intact.

There should be ample documentation on FedUp on the Fedora Wiki.