Explanation:

  1. Title Modification:

    • The title of the document is changed to "Bootstrap Layout Examples."
  2. Bootstrap CSS:

    • The <link> tag is included to link the Bootstrap CSS file (https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css).
  3. Comments:

    • Comments are added to the code for better understanding of each section, Bootstrap classes used, and their purposes.

Note: Ensure that the Bootstrap CSS link is correct and accessible.