Fill in missing documentation

lib/launchpad.rb

@@ -1,3 +1,7 @@
 require 'launchpad/settings'
 require 'launchpad/index'
 require 'launchpad/gui/application'
+
+# The main top level module for the launchpad gem.
+module Launchpad
+end

lib/launchpad/gui/application.rb

@@ -1,9 +1,11 @@
 require 'jrubyfx'
 
 module Launchpad
-  # Main application which is only created once at launch
+  # Main application which is only created once at launch.
   class Application < JRubyFX::Application
-    # Automatically called on {.launch}
+    # Automatically called on {Application.launch}
+    # @param [Java::JavafxStage::Stage] stage
+    #   automatically provided when {.launch} is called.
     def start(stage)
       stage.title = 'Launchpad'
       stage.width = 800

lib/launchpad/settings.rb

@@ -1,6 +1,6 @@
 module Launchpad
   # Provides default settings and allows user customization through creation of
-  # a yaml file for overrides
+  # a yaml file for overrides.
   class Settings
     DEFAULT = {
       local_index_path: 'index',