Limit the number of comments added to example entries

[schalkneethling]

I don't think the comments are always worth the space the occupy in pages like https://mdn.github.io/interactive-examples/pages/css/animation, especially where they all say the same thing. I feel that the comment showing the definition of slidein is not worth the space it consumes either.

[schalkneethling]

Definitely. Some of these were added to show what can be done, while others are there because I felt it needed it. We can definitely agree(and document) on a standard we should all adhere to when it comes to adding comments to the example choices.