release version 9.0

Problem:    About time to release Vim 9.0.
Solution:   Update the version number everywhere.
diff --git a/runtime/doc/hebrew.txt b/runtime/doc/hebrew.txt
index 62689e2..2644f81 100644
--- a/runtime/doc/hebrew.txt
+++ b/runtime/doc/hebrew.txt
@@ -1,4 +1,4 @@
-*hebrew.txt*    For Vim version 8.2.  Last change: 2019 May 05
+*hebrew.txt*    For Vim version 9.0.  Last change: 2019 May 05
 
 
 	   VIM REFERENCE MANUAL    by Ron Aaron (and Avner Lottem)