More helpful hints and germane advice for wannabe nsis users

git-svn-id: http://svn.osgeo.org/qgis/branches/Release-0_8_0@6668 c8812cc2-4d05-0410-92ff-de0c093fc19c

win_build/README.txt

@@ -19,3 +19,14 @@ broken at time of writing this. Use the
 one provided in this directory instead
 (still copy it to your nsis include dir 
 though).
+
+The NSIS installer now expects the qgis 
+binaries to be packaged to exist in 
+c:\Program Files\qgis<version> (the old
+c:\dev\cpp\qgis\qgs-release path is deprecated)
+
+Set the PRODUCT_VERSION_NUMBER in qgis.nsis 
+before running. This will allow having multiple 
+development versions on the same machine and 
+being able to package them without issue.
+