Remove generated files from source control

[grant]

This PR #140 introduced 21,838 lines of mostly HTML/non-Cloud SDK code into master.

It introduces files not related to this repo:
https://github.com/cloudevents/sdk-javascript/tree/master/docs/fonts

For example, these files were not hand-written and aren't expected to be added to source control:

@lance can we use gh-pages instead for this or somehow not include these files in master? This is common for most projects and will keep PRs slim. Or let's just use md files rather than HTML files.

[grant]

A docs/ folder is simply not very node-like.

Feel free to look at the way any of the top npm packages document their modules for comparison:
https://www.npmjs.com/browse/depended

[grant]

This was fixed in #194.