man: Add documentation for output seat confining
v2: Add some explanation about the default seat
diff --git a/man/weston.ini.man b/man/weston.ini.man
index c3e5747..9c22b3f 100644
--- a/man/weston.ini.man
+++ b/man/weston.ini.man
@@ -288,6 +288,15 @@
.BR "flipped-270 " "Flipped and 90 degrees counter clockwise"
.fi
.RE
+.TP 7
+.BI "seat=" name
+The logical seat name that that this output should be associated with. If this
+is set then the seat's input will be confined to the output that has the seat
+set on it. The expectation is that this functionality will be used in a
+multiheaded environment with a single compositor for multiple output and input
+configurations. The default seat is called "default" and will always be
+present. This seat can be constrained like any other.
+.RE
.SH "INPUT-METHOD SECTION"
.TP 7
.BI "path=" "/usr/libexec/weston-keyboard"