Merge pull request #8839 from irachex/dns-search-doc

Add docs for --dns-search=.

docs/sources/reference/commandline/cli.md

@@ -119,7 +119,7 @@ for un-encrypted, and port `2376` for encrypted communication with the daemon.
 > and greater are supported. Protocols SSLv3 and under are not supported anymore
 > for security reasons.
 
-On Systemd based systems, you can communicate with the daemon via 
+On Systemd based systems, you can communicate with the daemon via
 [systemd socket activation](http://0pointer.de/blog/projects/socket-activation.html), use
 `docker -d -H fd://`. Using `fd://` will work perfectly for most setups but
 you can also specify individual sockets: `docker -d -H fd://3`. If the
@@ -505,7 +505,7 @@ Creates a new container.
       --cpuset=""                CPUs in which to allow execution (0-3, 0,1)
       --device=[]                Add a host device to the container (e.g. --device=/dev/sdc:/dev/xvdc:rwm)
       --dns=[]                   Set custom DNS servers
-      --dns-search=[]            Set custom DNS search domains
+      --dns-search=[]            Set custom DNS search domains (Use --dns-search=. if you don't wish to set the search domain)
       -e, --env=[]               Set environment variables
       --entrypoint=""            Overwrite the default ENTRYPOINT of the image
       --env-file=[]              Read in a line delimited file of environment variables
@@ -1015,7 +1015,7 @@ used, which is observable by the process being suspended. With the cgroups freez
 the process is unaware, and unable to capture, that it is being suspended,
 and subsequently resumed.
 
-See the 
+See the
 [cgroups freezer documentation](https://www.kernel.org/doc/Documentation/cgroups/freezer-subsystem.txt)
 for further details.
 
@@ -1207,7 +1207,7 @@ removed before the image is removed.
       -d, --detach=false         Detached mode: run the container in the background and print the new container ID
       --device=[]                Add a host device to the container (e.g. --device=/dev/sdc:/dev/xvdc:rwm)
       --dns=[]                   Set custom DNS servers
-      --dns-search=[]            Set custom DNS search domains
+      --dns-search=[]            Set custom DNS search domains (Use --dns-search=. if you don't wish to set the search domain)
       -e, --env=[]               Set environment variables
       --entrypoint=""            Overwrite the default ENTRYPOINT of the image
       --env-file=[]              Read in a line delimited file of environment variables
@@ -1595,7 +1595,7 @@ them to [*Share Images via Repositories*](
 The `docker unpause` command uses the cgroups freezer to un-suspend all
 processes in a container.
 
-See the 
+See the
 [cgroups freezer documentation](https://www.kernel.org/doc/Documentation/cgroups/freezer-subsystem.txt)
 for further details.