Add help command

README.md

@@ -202,6 +202,10 @@ Build or rebuild services.
 
 Services are built once and then tagged as `project_service`, e.g. `figtest_db`. If you change a service's `Dockerfile` or the contents of its build directory, you can run `fig build` to rebuild it.
 
+#### help
+
+Get help on a command.
+
 #### kill
 
 Force stop service containers.

fig/cli/main.py

@@ -76,6 +76,7 @@ class TopLevelCommand(Command):
 
     Commands:
       build     Build or rebuild services
+      help      Get help on a command
       kill      Kill containers
       logs      View output from containers
       ps        List containers
@@ -99,6 +100,17 @@ class TopLevelCommand(Command):
         """
         self.project.build(service_names=options['SERVICE'])
 
+    def help(self, options):
+        """
+        Get help on a command.
+
+        Usage: help COMMAND
+        """
+        command = options['COMMAND']
+        if not hasattr(self, command):
+            raise NoSuchCommand(command, self)
+        raise SystemExit(getdoc(getattr(self, command)))
+
     def kill(self, options):
         """
         Kill containers.