adjust and clarify build instructions
Reviewed-by: ?

diff --git a/README.txt b/README.txt
--- a/README.txt
+++ b/README.txt
@@ -7,6 +7,7 @@ This is a Mercurial patch repository.
   See http://openjdk.java.net/projects/mlvm/ for more information
   about the Da Vinci Machine Project.
 
+  See also the wiki at http://wikis.sun.com/display/mlvm/Home .
 
 == Organization
 
@@ -15,6 +16,10 @@ Commits in the mlvm repositories do not 
 Commits in the mlvm repositories do not update the full source trees, only the patches.  To make this clear, when a commit occurs in a patch repository, we will refer to it specifically as a "patch commit".
 
 === Patches
+
+Make sure you have enabled the Mercurial mq extension with the following lines in your ".hgrc" file:
+	[extensions] 
+	mq =
 
 All patch files must end with the suffix ".patch".
 
@@ -92,6 +97,11 @@ Make a directory which will contain both
 	$ ls -il patches/hotspot/series sources/hotspot/.hg/patches/series
 	(should be identical files)
 	$ guards="buildable testable $(sh patches/make/current-release.sh)"
-	$ sh patches/make/each-patch-repo.sh hg qselect --reapply $guards
+	$ sh patches/make/each-patch-repo.sh hg qselect --pop $guards
+	$ sh patches/make/each-patch-repo.sh hg qpush -a
 
-TO DO: Put the details in patches/Makefilem, with a simple build target.
+The last command may produce output about patches being skipped.  This is correct, because the setting of $guards will ensure that only buildable and testable patches will be applied.
+
+(To apply other sets of patches, adjust the guard settings and/or use qpush to refer to specific desired patches.  Do not make permanent edits to the series file, unless they reflect true changes of development status.)
+
+TO DO: Put the details for setup and build in patches/Makefilem, with a simple build target.