markup: enable guessSyntax

This option will be necessary to maintain reasonable codeblock formatting in development once we add a custom language for YAGPDB templates (which will not be recognized by the default Hugo highlighter.)

Author: jo3-l

config/_default/markup.toml

@@ -23,6 +23,7 @@ defaultMarkdownHandler = "goldmark"
   hl_inline = false
   codeFences = true
   noClasses = false
+  guessSyntax = true
 
 [tableOfContents]
   endLevel = 3