Update title for command-line completion docs.

Signed-off-by: Daniel Nephin <[email protected]>

docs/completion.md

@@ -1,6 +1,6 @@
 <!--[metadata]>
 +++
-title = "Command Completion"
+title = "Command-line Completion"
 description = "Compose CLI reference"
 keywords = ["fig, composition, compose, docker, orchestration, cli,  reference"]
 [menu.main]
@@ -9,7 +9,7 @@ weight=3
 +++
 <![end-metadata]-->
 
-# Command Completion
+# Command-line Completion
 
 Compose comes with [command completion](http://en.wikipedia.org/wiki/Command-line_completion)
 for the bash and zsh shell.