manpage: Add escaping for hyphen used as minus

As pointed out by Debian lintian, options with '-' might not be
copy/pastable if formatted with an unescaped '-' character.

diff --git a/notmuch.1 b/notmuch.1
index 2c33749767392ccae25be03be645bc01c4561035..e4eed60fc95e5f828f940b4efda1a094f34c3180 100644 (file)
--- a/notmuch.1
+++ b/notmuch.1
@@ -169,31 +169,31 @@ the authors of the thread and the subject.
 .B threads
 
 Output the thread IDs of all threads with any message matching the
-search terms, either one per line (--format=text) or as a JSON array
-(--format=json).
+search terms, either one per line (\-\-format=text) or as a JSON array
+(\-\-format=json).
 .RE
 .RS 4
 .TP 4
 .B messages
 
 Output the message IDs of all messages matching the search terms,
-either one per line (--format=text) or as a JSON array
-(--format=json).
+either one per line (\-\-format=text) or as a JSON array
+(\-\-format=json).
 .RE
 .RS 4
 .TP 4
 .B files
 
 Output the filenames of all messages matching the search terms, either
-one per line (--format=text) or as a JSON array (--format=json).
+one per line (\-\-format=text) or as a JSON array (\-\-format=json).
 .RE
 .RS 4
 .TP 4
 .B tags
 
 Output all tags that appear on any message matching the search terms,
-either one per line (--format=text) or as a JSON array
-(--format=json).
+either one per line (\-\-format=text) or as a JSON array
+(\-\-format=json).
 .RE
 .RE