First stage of splitting out

Splitting out docs
Fixing location of help
entering in changes from testing
Filling in some missing structure
Updating with the comments from Nathan
Updating with the comments from Nathan
Updating after talk with Evan/Nathan

Signed-off-by: Mary Anthony <mary@docker.com>

docs/reference/ls.md

@@ -0,0 +1,50 @@
+<!--[metadata]>
++++
+title = "ls"
+description = "List machines"
+keywords = ["machine, ls, subcommand"]
+[menu.main]
+parent="smn_machine_subcmds"
++++
+<![end-metadata]-->
+
+# ls
+
+```
+Usage: docker-machine ls [OPTIONS] [arg...]
+
+List machines
+
+Options:
+
+   --quiet, -q					Enable quiet mode
+   --filter [--filter option --filter option]	Filter output based on conditions provided
+```
+
+## Filtering
+
+The filtering flag (`-f` or `--filter)` format is a `key=value` pair. If there is more
+than one filter, then pass multiple flags (e.g. `--filter "foo=bar" --filter "bif=baz"`)
+
+The currently supported filters are:
+
+* driver (driver name)
+* swarm (swarm master's name)
+* state (`Running|Paused|Saved|Stopped|Stopping|Starting|Error`)
+
+## Examples
+
+```
+$ docker-machine ls
+NAME   ACTIVE   DRIVER       STATE     URL
+dev             virtualbox   Stopped
+foo0            virtualbox   Running   tcp://192.168.99.105:2376
+foo1            virtualbox   Running   tcp://192.168.99.106:2376
+foo2   *        virtualbox   Running   tcp://192.168.99.107:2376
+```
+
+```
+$ docker-machine ls --filter driver=virtualbox --filter state=Stopped
+NAME   ACTIVE   DRIVER       STATE     URL   SWARM
+dev             virtualbox   Stopped
+```