Adds section on how to configure whether messages are automatically
marked as read.
Adds instructions to manually mark all messages as read, or mark all
messages in a stream or topic as read.
Adds the all messages tab image icon.
Fixes: #22915.
This help center article needs to be restructured before adding
documentation for mobile app users.
Splits the article into three sections so that we can document how
to mark messages as read on scroll or manually mark all messages
as read.
Adds "Related articles" section with cross-links.
Updates references to keyboard keys in the help center docs to use
`<kbd>` HTML elements, which also means updating them to be as the
key would appear on a keyboard.
Previously, uppercase and lowercase letters were used to indicate
when/if the `Shift` key was being used, and even that was not
consistent throughout the documentation.
For CSS styling, adds a similar rule for `<kbd>` elements that is
used in `/static/styles/app_components.css`. And updates the CSS
class used in `/static/js/portico/help.js` for `adjust_mac_shortcuts`
accordingly.
Also, takes advantage of revising these pages for making small
updates for current help center documentation practices.
Alya Abbott
David Rosa
Lauryn Menard
Aman Agrawal
SiddharthVarshney
Rishi Gupta