add CHANGES entry for vos

CHANGES

@@ -29,15 +29,22 @@ and the PG Trac http://proofgeneral.inf.ed.ac.uk/trac
 
 *** new menu Coq -> Auto Compilation for all background compilation options
 
+*** support for 8.11 vos compilation
+
+    See menu Coq -> Auto Compilation -> vos compilation, option
+    coq-compile-vos and subsection "11.3.3 Quick and inconsistent
+    compilation" in the Coq reference manual.
+
 *** support for 8.5 quick compilation
 
-    See new menu Coq -> Auto Compilation. Select "no quick" as
-    long as you have not switched to "Proof using" to compile
-    without -quick. Select "quick no vio2vo" to use -quick
-    without vio2vo (and guess what "quick and vio2vo" means ;-),
-    select "ensure vo" to ensure a sound development. See the
+    See new menu Coq -> Auto Compilation -> Quick compilation.
+    Select "no quick" as long as you have not switched to "Proof
+    using" to compile without -quick. Select "quick no vio2vo" to
+    use -quick without vio2vo (and guess what "quick and vio2vo"
+    means ;-), select "ensure vo" to ensure a sound development.
+    Quick compilation is only supported for Coq < 8.11. See the
     option `coq-compile-quick' or the subsection "11.3.3 Quick
-    compilation and .vio Files" in the Coq reference manual.
+    and inconsistent compilation" in the Coq reference manual.
 
 *** new option coq-compile-keep-going (in menu Coq -> Auto Compilation)