• Developer: Scott Granneman (forked from Travis Almand)
• Install it with one of these methods:
  • Use the Brackets Extension Manager
  • Download https://github.com/rsgranne/Brackets-HTML-Templates-Updated/zipball/master & install it by dragging the ZIP file onto the Extensions Manager window
• What it does: “Inserts HTML from a pre-made list of templates”, including HTML5, Bootstrap 3, & Bootstrap 4
• How to use it: Edit > HTML Templates, then choose the appropriate template

For more info, see the Brackets-HTML-Templates-Updated project page at GitHub.