Documentation for bash completion

Signed-off-by: Harald Albers <github@albersweb.de>

docs/completion.md

@@ -0,0 +1,33 @@
+---
+layout: default
+title: Command Completion
+---
+
+Command Completion
+==================
+
+Fig comes with [command completion](http://en.wikipedia.org/wiki/Command-line_completion)
+for the bash shell.
+
+Installing Command Completion
+-----------------------------
+
+Make sure bash completion is installed. If you use a current Linux in a non-minimal installation, bash completion should be available.
+On a Mac, install with `brew install bash-completion`
+ 
+Place the completion script in `/etc/bash_completion.d/` (`/usr/local/etc/bash_completion.d/` on a Mac), using e.g. 
+
+     curl -L https://raw.githubusercontent.com/docker/fig/master/contrib/completion/bash/fig > /etc/bash_completion.d/fig
+ 
+Completion will be available upon next login.
+
+Available completions
+---------------------
+Depending on what you typed on the command line so far, it will complete
+
+ - available fig commands
+ - options that are available for a particular command
+ - service names that make sense in a given context (e.g. services with running or stopped instances or services based on images vs. services based on Dockerfiles). For `fig scale`, completed service names will automatically have "=" appended.
+ - arguments for selected options, e.g. `fig kill -s` will complete some signals like SIGHUP and SIGUSR1.
+
+Enjoy working with fig faster and with less typos!

docs/install.md

@@ -20,6 +20,8 @@ Next, install Fig:
 
     curl -L https://github.com/docker/fig/releases/download/1.0.1/fig-`uname -s`-`uname -m` > /usr/local/bin/fig; chmod +x /usr/local/bin/fig
 
+Optionally, install [command completion](completion.html) for the bash shell.
+
 Releases are available for OS X and 64-bit Linux. Fig is also available as a Python package if you're on another platform (or if you prefer that sort of thing):
 
     $ sudo pip install -U fig