runtime(doc): fix inconsistent indent (#14089)

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/vim9.txt b/runtime/doc/vim9.txt
index 0f5884b..7dd2ab0 100644
--- a/runtime/doc/vim9.txt
+++ b/runtime/doc/vim9.txt
@@ -2024,7 +2024,7 @@
 					    *import-legacy* *legacy-import*
 `:import` can also be used in legacy Vim script.  The imported namespace still
 becomes script-local, even when the "s:" prefix is not given. For example: >
-        import "myfile.vim"
+	import "myfile.vim"
 	call s:myfile.MyFunc()
 
 And using the "as name" form: >