release version 9.0

Problem:    About time to release Vim 9.0.
Solution:   Update the version number everywhere.
diff --git a/runtime/doc/farsi.txt b/runtime/doc/farsi.txt
index b6799cc..a2afab4 100644
--- a/runtime/doc/farsi.txt
+++ b/runtime/doc/farsi.txt
@@ -1,4 +1,4 @@
-*farsi.txt*     For Vim version 8.2.  Last change: 2019 May 05
+*farsi.txt*     For Vim version 9.0.  Last change: 2019 May 05
 
 
 		  VIM REFERENCE MANUAL    by Mortaza Ghassab Shiran