Skeleton DEMO - Remove items from the examples section

[turolopezsanabria]

In order to simplify the Skeleton demo, please adjust the following:

• Add Skeleton to the image placeholder as well
• Make all the Skeletons the same width
• For ALL examples, make a square example of 200px * 200px

https://user-images.githubusercontent.com/23620759/135512158-5351f22c-d839-44cf-aa30-ec45a8ddb899.mov

• Remove 2 of the 3 examples, leave just the one with the toggle to enable and disable the animation

https://user-images.githubusercontent.com/23620759/135511742-1168e8d6-2e3b-4ece-8af3-834086ab1887.mov