Fix the backquote escape problem

[RipplePiam]

• According to commonmark's instructions, backslash escapes do not work in code blocks, code spans, autolinks, or raw HTML.
• Backslash escapes are never needed, because one can always choose a string of n backtick characters as delimiters, where the code does not contain any strings of exactly n backtick characters.
• This allows you to include code that begins or ends with backtick characters, which must be separated by whitespace from the opening or closing backtick strings.