Merge pull request #8291 from mieciu/master

Source the bash_completion after installation

docs/sources/installation/ubuntulinux.md

@@ -31,6 +31,7 @@ To install the latest Ubuntu package (may not be the latest Docker release):
     $ sudo apt-get install docker.io
     $ sudo ln -sf /usr/bin/docker.io /usr/local/bin/docker
     $ sudo sed -i '$acomplete -F _docker docker' /etc/bash_completion.d/docker.io
+    $ source /etc/bash_completion.d/docker.io
 
 If you'd like to try the latest version of Docker: