runtime(doc): fix typo in vim9script help file (#14782)

This commit fixes a typo in the first example of the vim9script help
file. Trying to execute the given example before resulted in a "trailing
characters" error.

Signed-off-by: jbm950 <jmilam343@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/usr_52.txt b/runtime/doc/usr_52.txt
index 4aae5fe..8607cf9 100644
--- a/runtime/doc/usr_52.txt
+++ b/runtime/doc/usr_52.txt
@@ -1,4 +1,4 @@
-*usr_52.txt*	For Vim version 9.1.  Last change: 2024 May 05
+*usr_52.txt*	For Vim version 9.1.  Last change: 2024 May 16
 
 		     VIM USER MANUAL - by Bram Moolenaar
 
@@ -45,7 +45,7 @@
 	def GetReply(nr: number): string
 	  if nr == 42
 	     return 'yes'
-	  elseif nr = 22
+	  elseif nr == 22
 	     return 'maybe'
 	  else
 	     return 'no'