release version 9.0

Problem:    About time to release Vim 9.0.
Solution:   Update the version number everywhere.
diff --git a/runtime/doc/scroll.txt b/runtime/doc/scroll.txt
index 8035d3c..d43ecb2 100644
--- a/runtime/doc/scroll.txt
+++ b/runtime/doc/scroll.txt
@@ -1,4 +1,4 @@
-*scroll.txt*    For Vim version 8.2.  Last change: 2022 May 07
+*scroll.txt*    For Vim version 9.0.  Last change: 2022 May 07
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar