- Updates intro paragraph in Message formatting page.
- Change Markdown syntax -> Markdown formatting.
- Reorders items in the Writing messages section of the left sidebar.
Updated the title and description in the 'enable-emoticon-translation'
file and renamed the file accordingly. Added a new bullet point for
'time format' in the 'configure-new-user-settings.md' file and updated
the sidebar index by replacing the title 'Use 24-hour time' with
'Change the time format'.
These files are not Jinja2 templates, so there's no reason that they needed
to be inside `templates/zerver`. Moving them to the top level reflects their
importance and also makes it feel nicer to work on editing the help center content,
without it being unnecessary buried deep in the codebase.
