patch 8.2.0149: maintaining a Vim9 branch separately is more work

Problem:    Maintaining a Vim9 branch separately is more work.
Solution:   Merge the Vim9 script changes.
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index 876ddf3..847290e 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -6221,6 +6221,7 @@
 	  compiler/	compiler files |:compiler|
 	  doc/		documentation |write-local-help|
 	  ftplugin/	filetype plugins |write-filetype-plugin|
+	  import/	files that are found by `:import`
 	  indent/	indent scripts |indent-expression|
 	  keymap/	key mapping files |mbyte-keymap|
 	  lang/		menu translations |:menutrans|