[PATCH 3/3] doc: add more information on operators.

[David Bremner <david@tethera.net>]

More material borrowed from the wiki page on "searching"
---
 doc/man7/notmuch-search-terms.rst | 43 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 38 insertions(+), 5 deletions(-)

diff --git a/doc/man7/notmuch-search-terms.rst b/doc/man7/notmuch-search-terms.rst
index 3b27053..a315fbe 100644
--- a/doc/man7/notmuch-search-terms.rst
+++ b/doc/man7/notmuch-search-terms.rst
@@ -118,17 +118,50 @@ The time range can also be specified using timestamps with a syntax of:
 Each timestamp is a number representing the number of seconds since
 1970-01-01 00:00:00 UTC.
 
-In addition to individual terms, multiple terms can be combined with
-Boolean operators ( **and**, **or**, **not** , etc.). Each term in the
-query will be implicitly connected by a logical AND if no explicit
-operator is provided, (except that terms with a common prefix will be
-implicitly combined with OR until we get Xapian defect #402 fixed).
+Operators
+---------
 
+In addition to individual terms, multiple terms can be combined with
+Boolean operators ( **and**, **or**, **not**, and **xor**). Each term
+in the query will be implicitly connected by a logical AND if no
+explicit operator is provided, (except that terms with a common prefix
+will be implicitly combined with OR until we get Xapian defect #402
+fixed).  The shorthand '-<term>' can be used for 'not <term>' but
+unfortunately this does not work at the start of an expression.
 Parentheses can also be used to control the combination of the Boolean
 operators, but will have to be protected from interpretation by the
 shell, (such as by putting quotation marks around any parenthesized
 expression).
 
+In addition to the standard boolean operators, Xapian provides several
+operators specific to text searching.
+
+::
+
+        notmuch search term1 NEAR term2
+
+will return results where term1 is within 10 words of term2. The
+threshold can be set like this:
+
+::
+
+        notmuch search term1 NEAR/2 term2
+
+The search
+
+::
+
+        notmuch search term1 ADJ term2
+
+will return results where term1 is within 10 words of term2, but in the
+same order as in the query. The threshold can be set the same as with
+NEAR:
+
+::
+
+        notmuch search term1 ADJ/7 term2
+
+
 Stemming
 --------
 
-- 
2.1.4