doc: add notmuch-properties(7)

We will want a user-facing place to record details about the use of
notmuch properties shortly.  This establishes a new manual page for
that purpose.

2 files changed, 56 insertions, 1 deletions

diff --git a/doc/man7/notmuch-properties.rst b/doc/man7/notmuch-properties.rst
new file mode 100644
index 00000000..8654077c
--- /dev/null
+++ b/doc/man7/notmuch-properties.rst
@@ -0,0 +1,53 @@
+==================
+notmuch-properties
+==================
+
+SYNOPSIS
+========
+
+**notmuch** **count** **property:**\ <*key*>=<*value*>
+
+**notmuch** **search** **property:**\ <*key*>=<*value*>
+
+**notmuch** **show** **property:**\ <*key*>=<*value*>
+
+**notmuch** **reindex** **property:**\ <*key*>=<*value*>
+
+**notmuch** **tag** +<*tag*> **property:**\ <*key*>=<*value*>
+
+
+**notmuch** **dump** **--include=properties**
+
+**notmuch** **restore** **--include=properties**
+
+DESCRIPTION
+===========
+
+Several notmuch commands can search for, modify, add or remove
+properties associated with specific messages.  Properties are
+key/value pairs, and a message can have more than one key/value pair
+for the same key.
+
+While users can select based on a specific property in their search
+terms with the prefix **property:**, the notmuch command-line
+interface does not provide mechanisms for modifying properties
+directly to the user.
+
+Instead, message properties are expected to be set and used
+programmatically, according to logic in notmuch itself, or in
+extensions to it.
+
+Extensions to notmuch which make use of properties are encouraged to
+report the specific properties used to the upstream notmuch project,
+as a way of avoiding collisions in the property namespace.
+
+SEE ALSO
+========
+
+**notmuch(1)**,
+**notmuch-dump(1)**,
+**notmuch-insert(1)**,
+**notmuch-new(1)**,
+**notmuch-reindex(1)**,
+**notmuch-restore(1)**,
+***notmuch-search-terms(7)**
diff --git a/doc/man7/notmuch-search-terms.rst b/doc/man7/notmuch-search-terms.rst
index c602eadb..637f7777 100644
--- a/doc/man7/notmuch-search-terms.rst
+++ b/doc/man7/notmuch-search-terms.rst
@@ -159,7 +159,8 @@ below).
 The **property:** prefix searches for messages with a particular
 <key>=<value> property pair. Properties are used internally by notmuch
 (and extensions) to add metadata to messages. A given key can be
-present on a given message with several different values.
+present on a given message with several different values.  See
+**notmuch-properties(7)** for more details.
 
 Operators
 ---------
@@ -429,6 +430,7 @@ SEE ALSO
 **notmuch-insert(1)**,
 **notmuch-new(1)**,
 **notmuch-reindex(1)**,
+**notmuch-properties(1)**,
 ***notmuch-reply(1)**,
 **notmuch-restore(1)**,
 **notmuch-search(1)**,