This removes a not needed inline code tag (back-tick) in the upgrading
chapter for 2.11.
If you are running the commands with a different user than the
compiled `ICINGA_USER` and `ICINGA_GROUP` CMake settings (`icinga` everywhere,
-except Debian with `nagios` for historical reasons`), ensure that this
+except Debian with `nagios` for historical reasons), ensure that this
user has the capabilities to change to a different user.
If you still encounter problems, run the aforementioned CLI commands as root,