NEWS: document notmuch reindex

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).

1 files changed, 13 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index d720c1e0..6d2bf138 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,19 @@ Out-of-tree builds
   has been dropped. The same can now be achieved more reliably using
   out-of-tree builds.
 
+Command Line Interface
+----------------------
+
+Support for re-indexing existing messages
+
+  There is a new subcommand, `notmuch reindex`, which re-indexes all
+  messages matching supplied search terms.  This permits users to
+  change the way specific messages are indexed.
+
+  Note that for messages with multiple variants in the message
+  archive, the recorded Subject: of may change upon reindexing,
+  depending on the order in which the variants are indexed.
+
 Encrypted Mail
 --------------