lispref/markers.texi small change

* doc/lispref/markers.texi (Overview of Markers):
Reword garbage collection, add cross-ref.

doc/lispref/ChangeLog

@@ -2,6 +2,7 @@
 
 	* markers.texi (The Region):
 	Briefly mention use-empty-active-region and region-active-p.
+	(Overview of Markers): Reword garbage collection, add cross-ref.
 
 2012-03-07  Chong Yidong  <cyd@gnu.org>
 

doc/lispref/markers.texi

@@ -58,6 +58,8 @@ with @code{insert-before-markers} (@pxref{Insertion}).
 relocate them if necessary.  This slows processing in a buffer with a
 large number of markers.  For this reason, it is a good idea to make a
 marker point nowhere if you are sure you don't need it any more.
+Markers that can no longer be accessed are eventually removed
+(@pxref{Garbage Collection}).
 
 @cindex markers as numbers
   Because it is common to perform arithmetic operations on a marker