The conversion script for help-beta assumes that all items in a numbered
list start with 1. which was a wrong assumption. This commit attempts to
fix that. We are not introducing any lint step to tackle this since it
will be easy to just check for this again before the cutover happens.
We do not change this for `numbered-list-examples.md` since that example
shows how the current numbered lists work and we might still want to
show that. We can decide what to do with that file once the time of
cutover arrives.
This includes changing the URL to #settings/preferences, with a
transparent redirect so that existing links, like the one from Welcome
Bot, continue to work.
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.
