Add note warning that OS X updates usually overwrite /etc/rc.

diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index 9295b14c614e535aa6fce54371a163e3e163ad5f..7e938cd61ed4144283f89c13d7ec36294700ae7f 100644 (file)
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -1,5 +1,5 @@
 
 
 
@@ -4427,7 +4427,9 @@ sysctl -w kern.sysv.shmseg
 sysctl -w kern.sysv.shmall
 
         In OS X 10.3, these commands have been moved to /etc/rc
-        and must be edited there.
+        and must be edited there.  Note that /etc/rc is usually
+        overwritten by OS X updates (such as 10.3.6 to 10.3.7) so you
+        should expect to have to redo your editing after each update.