runtime(rst): Style update

Minor style and whitespace changes to the reST syntax file, to sync with
the development branch.

related: #18566

Signed-off-by: Marshall Ward <marshall.ward@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/syntax/rst.vim

@@ -2,8 +2,9 @@
 " Language: reStructuredText documentation format
 " Maintainer: Marshall Ward <marshall.ward@gmail.com>
 " Previous Maintainer: Nikolai Weibull <now@bitwi.se>
+" Reference: https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html
 " Website: https://github.com/marshallward/vim-restructuredtext
-" Latest Revision: 2020-03-31
+" Latest Revision: 2025-10-13
 
 if exists("b:current_syntax")
   finish
@@ -12,7 +13,8 @@ endif
 let s:cpo_save = &cpo
 set cpo&vim
 
-syn case ignore
+" reStructuredText is case-insensitive
+syntax case ignore
 
 syn match   rstTransition  /^[=`:.'"~^_*+#-]\{4,}\s*$/
 
@@ -97,6 +99,9 @@ execute 'syn region rstExDirective contained matchgroup=rstDirective' .
 execute 'syn match rstSubstitutionDefinition contained' .
       \ ' /|.*|\_s\+/ nextgroup=@rstDirectives'
 
+
+"" Inline Markup ""
+
 function! s:DefineOneInlineMarkup(name, start, middle, end, char_left, char_right)
   " Only escape the first char of a multichar delimiter (e.g. \* inside **)
   if a:start[0] == '\'
@@ -190,6 +195,8 @@ execute 'syn match rstHyperlinkReference' .
 syn match   rstStandaloneHyperlink  contains=@NoSpell
       \ "\<\%(\%(\%(https\=\|file\|ftp\|gopher\)://\|\%(mailto\|news\):\)[^[:space:]'\"<>]\+\|www[[:alnum:]_-]*\.[[:alnum:]_-]\+\.[^[:space:]'\"<>]\+\)[[:alnum:]/]"
 
+" `code` is the standard reST directive for source code.
+" `code-block` and `sourcecode` are nearly identical directives in Sphinx.
 syn region rstCodeBlock contained matchgroup=rstDirective
       \ start=+\%(sourcecode\|code\%(-block\)\=\)::\s*\(\S*\)\?\s*\n\%(\s*:.*:\s*.*\s*\n\)*\n\ze\z(\s\+\)+
       \ skip=+^$+