Update styleguide.md

[ntwb]

Follow up to #66 to update markdown format for https://developer.wordpress.org/coding-standards/styleguide/

This resolves most issues with this file except for these two issues:

styleguide.md:102:30 MD033/no-inline-html Inline HTML [Element: code]
styleguide.md:110:47 MD033/no-inline-html Inline HTML [Element: code]

For the first and last lines of this section of code:

wpcs-docs/styleguide.md

Lines 98 to 105 in 776433c

	Wrap inline code with <code>`\``</code> backticks:
	````
	```
	This is `inline code` wrapped with backticks
	```
	````
	When documenting an example, use the markdown <code>`\``</code> code block to demarcate the beginning and end of the code sample:

This had been previously tried, but the parser didn't like this change eb0aa61#diff-43a6652a89d7d4621d2a09e2f299221d56063e27e66431443b319451e8e82e0a

Can possibly add an ignore-directive for markdownlint for this