change text on licence page

see
https://trac.osgeo.org/grass/ticket/986#comment:18

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@41361 15284696-431f-4ddb-bdfa-cd5b030d7da7

mswindows/GRASS-Installer.nsi

@@ -339,6 +339,10 @@ FunctionEnd
 !insertmacro MUI_PAGE_WELCOME
 
 ;These indented statements modify settings for MUI_PAGE_LICENSE
+    !define MUI_LICENSEPAGE_TEXT_BOTTOM "GRASS is software libre. You are encouraged and legally \
+	entitled to copy, reinstall, modify, and redistribute this program \
+	for yourself and your friends under the terms of the GPL. Happy \
+	mapping!"
     !define MUI_LICENSEPAGE_BUTTON "Next >"
 !insertmacro MUI_PAGE_LICENSE "${PACKAGE_FOLDER}\GPL.TXT"