man: update query documentation

man/mu-query.7

@@ -279,6 +279,17 @@ maildir, you can do with a single '/':
 maildir:/
 .EX2
 
+If you have maildirs (or any fields) that include spaces, you need to
+quote them, ie.
+.EX1
+maildir:"/Sent Items"
+.EX2
+
+Note that from the command-line, such queries must be quoted:
+.EX1
+mu find 'maildir:"/Sent Items"'
+.EX2
+
 .SH MORE EXAMPLES
 
 Here are some simple examples of \fBmu\fR queries; you can make many
@@ -322,6 +333,17 @@ Find all messages with attached images:
 mime:image/*
 .EX2
 
+.SH CAVEATS
+
+With current Xapian versions, the apostroph character is considered
+part of a word. Thus, you cannot find \fID'Artagnan\fR by searching
+for \fIArtagnan\fR. So, include the apostroph in search or use a
+regexp search.
+
+Matching on spaces has changed compared to the old query-parser; this
+applies e.g. to Maildirs that have spaces in their name, such as
+\fISent Items\fR. See \fBMAILDIR\fR above.
+
 .SH AUTHOR
 
 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>