Expose deep links in the UI

[sindresorhus]

For example, in https://sindresorhus.com/playground/KeyboardShortcuts_Name/, it would be nice when I hovered over init?(raw​Value:​), it would show a link icon and clicking it would give me a direct deep link to that method. Like with headers in GitHub readme's.

[mattt]

That's a great idea, @sindresorhus.

For posterity, here's a screenshot of how GitHub renders heading anchors:

[mattt]

Fixed by #275