Added GitHub alert styles to bad/good code examples.

[kkevindev]

Added code blocks to alert boxes so the bad & good code examples are much easier to spot.

Before	After

Unfortunately you cannot change the "warning" and "tip" titles.

[TomasVotruba]

Thanks for the proposal. I like simpler syntax we use now.
Also "tip" is not really right word, "correct" or "fixed" would be 👌

[kkevindev]

@TomasVotruba Okay but if you look at this example, it's much more clear that the provided code in these examples give a warning (is bad code):

Before	After