* Update ssh_backend.md
* Update normalize_output_to_unicode_nfc.md
* Update strikethrough_position.md
* Update underline_position.md
* Update underline_thickness.md
* Fix lua config docs titles to be formatted as inline code
* Mention how suggested alphabet for quick select is choosen
* Mention update-status and update-right-status for status_update_interval
* Fix docs for all keyassignments to be formatted as inline code
* Fix Lua object index titles
* Fix titles of `wezterm.*` module index pages
* Fix title of `Color` object & `wezterm.color` functions
We reduce titles from h2 to h1 because mkdocs defaults the page title to
the page file name if no h1 header is found.
* Unify title of all object methods
* Add index page for Gui events
Moved the gradient function into the color module, but kept an alias
under the old name.
Gradients now return color objects.
Converting colors to string now uses rgba format when alpha is not 100%.