Add documentation

MenuItemHandler.py

@@ -5,10 +5,29 @@
 #You should have received a copy of the GNU Affero General Public License along with this plug-in. If not, see <https://gnu.org/licenses/>.
 
 class MenuItemHandler:
+	"""
+	This class handles clicks when the user clicks on the context menu item in
+	the settings list.
+
+	An instance of this class is passed to the list model in QML's context menu.
+	"""
+
 	def __init__(self, plugin_controller) -> None:
+		"""
+		Constructs the menu item handler.
+		:param plugin_controller: The main Settings Guide class so that we can
+		open the guide.
+		"""
 		self._plugin_controller = plugin_controller
 
 	def sidebarMenuItemOnClickHandler(self, kwargs) -> None:
+		"""
+		Triggered when the user clicks the menu item in the context menu in the
+		settings list.
+		:param kwargs: Keyword arguments that the QML menu provided. This
+		function looks for the `key` keyword, which indicates the setting key
+		that the user clicked on.
+		"""
 		if "key" in kwargs:
 			article_key = kwargs["key"]
 			self._plugin_controller.startWelcomeGuideAndSelectArticle(article_key)