README: Mention that notmuch only supports maildir or mh format.

Justin B Rye pointed out (in Debian bug #566282) that a user with mail
in mbox format can spend a lot of time investigating notmuch before
realizing that mbox is not supported. Head that off with a more
detailed mention in the README blurb.

diff --git a/README b/README
index 2c570e1d2f7bbcc78d9e90408a3a5e167109b183..5f029c828280f6661ea045d2a06496214686cc82 100644 (file)
--- a/README
+++ b/README
@@ -1,8 +1,9 @@
 Notmuch - thread-based email index, search and tagging.
 
 Notmuch is a system for indexing, searching, reading, and tagging
-large collections of email messages. It uses the Xapian library to
-provide fast, full-text search with a convenient search syntax.
+large collections of email messages in maildir or mh format. It uses
+the Xapian library to provide fast, full-text search with a convenient
+search syntax.
 
 Notmuch is free software, released under the GNU General Public
 License version 3 (or later).