new(demo): add Annotation demo

[williaster]

📝 Documentation

This builds on #907 and

• adds a new /annotation demo
• adds an Annotation tile to the Gallery + as an example to /docs/annotation
• adds the new components to /docs/annotation

TODO

• add ResizeObserver polyfill info to Readme

Demo

Tile

[coveralls]

Pull Request Test Coverage Report for Build 348506057

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.01%) to 57.962%

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Totals
Change from base Build 348458839:	-0.01%
Covered Lines:	1576
Relevant Lines:	2533

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💛 - Coveralls