4.15.0

Enhancements

• Add logo and title customization to the masthead. [#2026]
• Add support to customize issue-term for utterances comment provider. [#2022]
• Allow custom canonical url on a page-by-page basis. [#2021]
• Update table of contents navigation based on scroll position to indicate which link is currently active in the viewport. [#2020]
• Clicking table of contents links changes URL has fragment. [#2019] [#2023]