runtime(html): update syntax script to sync by 250 minlines by default

closes: #14071

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/syntax.txt b/runtime/doc/syntax.txt
index 2f8d950..9449b75 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -1,4 +1,4 @@
-*syntax.txt*	For Vim version 9.1.  Last change: 2024 Jul 25
+*syntax.txt*	For Vim version 9.1.  Last change: 2024 Jul 30
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -1908,6 +1908,10 @@
 vimrc file: >
 	:let html_no_rendering=1
 
+By default Vim synchronises the syntax to 250 lines before the first displayed
+line.  This can be configured using: >
+	:let html_minlines = 500
+<
 HTML comments are rather special (see an HTML reference document for the
 details), and the syntax coloring scheme will highlight all errors.
 However, if you prefer to use the wrong style (starts with <!-- and