Wiki for using notmuch with Emacs is outdated

[David Bremner]

yangsheng6810 at gmail.com writes:

> The package name for `org-notmuch.el` was changed to `ol-notmuch` in the following commit in org-mode on March 2nd 2019.
>
> 499c0a50c * bad Prefix link-related libraries filenames with "ol"
>
> Therefore, the descriptions at https://notmuchmail.org/emacstips/#index24h2 need to be updated.
>

I guess it depends on version of org. I'm still running org-mode 9.2.3,
and the old name is present there.

In any case, feel free to add some notes about the changes in more
recent versions of org-mode; see [1] for how.

[1]: https://notmuchmail.org/wikiwriteaccess/