Merge Chapter 2 code

[chundhau]

Overview

The Chapter 2 code builds a skeleton single-page web app using HTML and CSS. This pull request merges the code from Chapter 2 into the main branch. Closes #1.

Details

The skeleton app includes the following user interface components:

• a favicon and app title in the app's browser title
• a top navigation bar with menu button, app icon, and app area title
• a expanding/contracting side menu with mode-specific items plus "About" and "Log Out"
• a bottom bar for switching between three app modes: "Feed," "Rounds," and "Courses"
• a floating action button for completing the most common task in the current mode.

A theme of Chapter 2 is designing web apps for accessibility through the use of semantic HTML and ARIA attributes. These have been used in the HTML code to enhance accessibility.

Here is a screenshot of the final state of the app at the end of Chapter 2:

Testing

I have tested the app via visual inspection. Additional testing using a screen reader emulator should be performed to assess the accessibility of the app.

[chundhau]

@warior4356 This PR is obsolete. I am actually going to delete the ch2 branch and re-build it from scratch once I have the new accessible app design finalized in the accessible-base-app branch. Hence, this PR will ultimately be deleted and replaced with a new one.