[PATCH v2] NEWS & doc: typing fixes

[David Bremner]

Tomi Ollila <tomi.ollila at iki.fi> writes:

> Some inconsistent formatting in NEWS for 0.19, 0.18 & 0.17 fixed.
>
> Extra `*` when making bold text in doc/man1/notmuch-search.rst removed.

Pushed,

d