Update deb-triggers(5) and dpkg-trigger(1)

Update deb-triggers(5) and dpkg-trigger(1) to add a reference to
/usr/share/doc/dpkg/triggers.txt.gz.

debian/changelog

@@ -12,6 +12,8 @@ dpkg (1.15.1) UNRELEASED; urgency=low
   * Drop support of debian/control's “Format” field used by dpkg-source while
     it's not too late. Instead debian/source/format should be used to indicate
     the desired source package format.
+  * Update deb-triggers(5) and dpkg-trigger(1) to add a reference to
+    /usr/share/doc/dpkg/triggers.txt.gz. Closes: #519717
 
   [ Guillem Jover ]
   * Fix typo in dpkg output (‘unexecpted’ → ‘unexpected’). Closes: #519082

man/deb-triggers.5

@@ -48,4 +48,5 @@ package.
 .
 .SH SEE ALSO
 .BR dpkg\-trigger (1),
-.BR dpkg (1).
+.BR dpkg (1),
+.BR /usr/share/doc/dpkg/triggers.txt.gz .

man/dpkg-trigger.1

@@ -61,5 +61,5 @@ the trigger.
 Just test, do not actually change anything.
 .
 .SH SEE ALSO
-.BR dpkg "(1), " deb-triggers (5).
+.BR dpkg "(1), " deb-triggers "(5), " /usr/share/doc/dpkg/triggers.txt.gz .