[PATCH] NEWS: document notmuch reindex

[David Bremner]

Daniel Kahn Gillmor <dkg at fifthhorseman.net> writes:

> Describe the introduction of the "reindex" subcommand.  This blurb
> acknowledges Subject: instability under reindexing when multiple
> copies exist (suggesting that this is something that needn't
> necessarily hold up a release).

I hemmed and hawed about giving a more precise statement, but eventually
I decided that some general warning is good enough for now.

pushed,

d