Remove Fedora 22 from RPM build as it is EOL

Fedora 22 reached end of life on July 19th, and
will no longer receive updates;

https://fedoramagazine.org/fedora-22-end-of-life-2016-july/

With the recent release of Fedora 24, Fedora 22 will officially enter End Of
Life (EOL) status on July 19th, 2016. After July 19th, all packages in the
Fedora 22 repositories will no longer receive security, bugfix, or enhancement
updates, and no new packages will be added to the Fedora 22 collection.

Upgrading to Fedora 23 or Fedora 24 before July 19th 2016 is highly recommended
for all users still running Fedora 22.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docs/reference/commandline/dockerd.md

@@ -949,11 +949,6 @@ these resources are name-based, not id-based.  If the numeric ID information
 provided does not exist as entries in `/etc/passwd` or `/etc/group`, daemon
 startup will fail with an error message.
 
-> **Note:** On Fedora 22, you have to `touch` the `/etc/subuid` and `/etc/subgid`
-> files to have ranges assigned when users are created.  This must be done
-> *before* the `--userns-remap` option is enabled. Once these files exist, the
-> daemon can be (re)started and range assignment on user creation works properly.
-
 **Example: starting with default Docker user management:**
 
 ```bash