Clean up and improve Annotation stories

[axelboc]

While working on refactoring Html in #1465 , I noticed that the Annotation stories were in need of a good clean-up.

I took full advantage of Storybook by splitting each annotation example into its own story, which means that the controls now work as expected and the props are properly listed in the Docs page.

I also:

• removed the SVG story, since Annotation is no longer the recommended way to render SVG elements;
• added a story to document overflowCanvas.

This actually uncovered a bug: annotations that overflow the canvas are not positioned properly, since they are positioned relatively to the canvasWrapper element, which includes the axes. I have an idea to fix this, but I'll continue working on declarative axes first.

[loichuder]

Just a thought: it would be nice to highlight the (10, 16) point above with a red cross for example.

[axelboc]

Good call! I kept it quite discrete so the text remains readable when the annotation is centred.