The top-level template object `extra_javascript` gets soft-deprecated because it still reports only a list of plain strings.
Themes need to take action and pick up the new config keys from `config.extra_javascript` instead.
The result is exactly equivalent, just different syntax -- one that doesn't look weird in vanilla Markdown parsers such as on GitHub.
The output HTML before/after is equivalent , other than adding `<p class="admonition-title">Block</p>` in two cases, which I hid with CSS.
This also contributes to fixing the currently-present markdownlint MD053 violations, as it can't scan inside admonitions.
Add 'markdown-callouts' to dependencies and bump Markdown dep.
The homepage has been redesigned. The "Installation" and "Getting Started" sections were moved to their own respective pages. Then, the homepage was restyled so that the list of features appear as a grid of cards.
The developer specific pages were moved to a new section: `dev-guide`. Any old URLs redirect to the new ones.
