docs: initial draft of NEWS for 0.20

This is meant as much to jog people's memory as to be definitive.

NEWS

@@ -10,11 +10,66 @@ There is a new `mimetype:` search prefix
   content-type of attachments, which is now indexed. See the
   `notmuch-search-terms` manual page for details.
 
+Path to gpg is now configurable
+
+  On systems with multiple versions of gpg, you can tell
+  notmuch which one to use by setting `crypto.gpg_path`
+
+New command, `notmuch-emacs-mua`
+
+  This new wrapper script is intended to be a drop in replacement for
+  mutt to compose and send mail using `notmuch-emacs`
+
+Emacs
+-----
+
+Avoid rendering large text attachements.
+
+Improved rendering of CID references in HTML.
+
+Vim
+---
+
+Vim client now respects excluded tags.
+
+Notmuch-Mutt
+------------
+
+Support messages without Message-IDs.
+
+Library
+-------
+
+Undeprecate single message mboxes
+
+  It seems more trouble to remove this feature than expected, so
+  `notmuch new` will no longer nag about mboxes with a single message.
+
+New error logging facility
+
+  Clients should call `notmuch_database_status_string` to retrieve
+  output formerly printed to stderr.
+
+Several bug fixes related to stale iterators
+
+New status code returning API for n_query_search_{messages,thread}
+
+Fix for library `install_name` on Mac OS X
+
+Fix for rounding of seconds
+
 Documentation
 -------------
 
-Support for using rst2man in place of sphinx to build the
-docmumentation has been removed.
+Sphinx is now mandatory to build docs
+
+  Support for using rst2man in place of sphinx to build the
+  docmumentation has been removed.
+
+Improved notmuch-search-terms.7
+
+  The man page `notmuch-search-terms(7)` has been extended, merging
+  some material from the relicensed wiki.
 
 Contrib
 -------