Update lib/lexer_mdx.mll

Co-authored-by: Nathan Rebours <nathan.p.rebours@gmail.com>

Author: Julow

lib/lexer_mdx.mll

@@ -16,7 +16,7 @@ let labels l =
     failwith msg
 }
 
-let eol = '\n' | '\r' '\n' | eof
+let eol = '\n' | "\r\n" | eof
 let ws = [' ' '\t']
 
 let until_eol = [^'\n' '\r']