Markdown code blocks migration part 7 (#20547)

lib/packages/docutils/highlite.nim

@@ -13,7 +13,7 @@
 ##
 ## You can use this to build your own syntax highlighting, check this example:
 ##
-## .. code:: Nim
+##   ```Nim
 ##   let code = """for x in $int.high: echo x.ord mod 2 == 0"""
 ##   var toknizr: GeneralTokenizer
 ##   initGeneralTokenizer(toknizr, code)
@@ -31,19 +31,20 @@
 ##     else:
 ##       echo toknizr.kind # All the kinds of tokens can be processed here.
 ##       echo substr(code, toknizr.start, toknizr.length + toknizr.start - 1)
+##   ```
 ##
 ## The proc `getSourceLanguage` can get the language `enum` from a string:
-##
-## .. code:: Nim
+##   ```Nim
 ##   for l in ["C", "c++", "jAvA", "Nim", "c#"]: echo getSourceLanguage(l)
+##   ```
 ##
 ## There is also a `Cmd` pseudo-language supported, which is a simple generic
 ## shell/cmdline tokenizer (UNIX shell/Powershell/Windows Command):
 ## no escaping, no programming language constructs besides variable definition
 ## at the beginning of line. It supports these operators:
-##
-## .. code:: Cmd
-##    &  &&  |  ||  (  )  ''  ""  ;  # for comments
+##   ```Cmd
+##   &  &&  |  ||  (  )  ''  ""  ;  # for comments
+##   ```
 ##
 ## Instead of escaping always use quotes like here
 ## `nimgrep --ext:'nim|nims' file.name`:cmd: shows how to input ``|``.