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

> @@ -89,8 +89,9 @@ <h2 id="toc">Table of Contents</h2>
>      <li><a href="#es6">Custom Elements and ECMAScript 6</a></li>
>      <li><a href="#semantics">Custom Element Semantics</a>
>      <ol>
> -        <li><a href="#custom-tag-semantics">Custom Tag Semantics</a></li>
> -        <li><a href="#type-extension-semantics">Type Extension Semantics</a></li>
> +     <li><a href="#custom-tag-semantics">Custom Tag Semantics</a></li>

Would love to keep indentation here.

---
Reply to this email directly or view it on GitHub:
https://github.com/w3c/webcomponents/pull/29/files#r21840361