Resolve "Add comments to all files"

Closes #67 (closed)

assets/themes/Theme.js

-import React from "react";
 import { DefaultTheme } from "react-native-paper";
 
+/**
+ * Defines the overall theme of the application. See https://callstack.github.io/react-native-paper/theming.html for more documentation. 
+ */
+
 const theme = {
   ...DefaultTheme,
   roundness: 2,