[webcomponents] extended examples and added developer advice section (#29)

note:
'taco-button' tag name borrowed from Marcy Sutton
'tequila-button' tag name borrowed from Leonie Watson
You can merge this Pull Request by running:

  git pull https://github.com/stevefaulkner/webcomponents gh-pages

Or you can view, comment on it, or merge it online at:

  https://github.com/w3c/webcomponents/pull/29

-- Commit Summary --

  * extended examples and added advice
  * added details about keyboard requirements

-- File Changes --

    M spec/custom/index.html (50)

-- Patch Links --

https://github.com/w3c/webcomponents/pull/29.patch
https://github.com/w3c/webcomponents/pull/29.diff

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/webcomponents/pull/29