Fix #470: consistently use "authors" instead of "developers"

All usages are in sections that will upstream into HTML, which prefers the term "authors."

spec/custom/index.html

@@ -328,7 +328,7 @@ <h4>Drawbacks of custom tags</h4>
 
 <p>Even with this rather-complicated element definition, the element is not a pleasure to use for consumers: it will be continually "sprouting" <code><a href="https://html.spec.whatwg.org/#attr-tabindex">tabindex</a></code> and <code>aria-*</code> attributes of its own volition. This is because as of now there is no way to specify default accessibility semantics or focus behavior for custom elements, forcing the use of these attributes to do so (even though they are usually reserved for allowing the consumer to override default behavior).</p>
 
-<p>In contrast, a simple <a>type extension</a>, as shown in the previous section, would automatically inherit the semantics and behavior of the <a href="https://html.spec.whatwg.org/#the-button-element"><code>button</code></a> element, with no need to implement these behaviors manually. In general, for any element with nontrivial behavior and semantics which builds on top of existing elements of HTML, <a lt="type extension">type extensions</a> will be easier to developer, maintain, and consume.</p>
+<p>In contrast, a simple <a>type extension</a>, as shown in the previous section, would automatically inherit the semantics and behavior of the <a href="https://html.spec.whatwg.org/#the-button-element"><code>button</code></a> element, with no need to implement these behaviors manually. In general, for any element with nontrivial behavior and semantics which builds on top of existing elements of HTML, <a lt="type extension">type extensions</a> will be easier to develop, maintain, and consume.</p>
 
 </section>
 
@@ -392,7 +392,7 @@ <h4 id="custom-elements-upgrades-examples">Upgrading elements after their creati
 <section>
 <h3 id="custom-element-conformance">Requirements for custom element constructors</h3>
 
-<p>When authoring <a lt="custom element constructor">custom element constructors</a>, developers are bound by the following <a href="https://html.spec.whatwg.org/#conformance-requirements-for-authors">conformance requirements</a>:</p>
+<p>When authoring <a lt="custom element constructor">custom element constructors</a>, authors are bound by the following <a href="https://html.spec.whatwg.org/#conformance-requirements-for-authors">conformance requirements</a>:</p>
 
 <ul>
     <li>A parameter-less call to <code>super()</code> must be the first statement in the constructor body, to establish the correct prototype chain and <code>this</code> value before any further code is run.</li>
@@ -410,7 +410,7 @@ <h3 id="custom-element-conformance">Requirements for custom element constructors
 <section>
 <h3 id="custom-elements-core-concepts">Core concepts</h3>
 
-<p>A <dfn id="dfn-custom-element">custom element</dfn> is an <a href="https://dom.spec.whatwg.org/#concept-element">element</a> that is <a>custom</a>. Informally, this means that its constructor and prototype are defined by the web developer, instead of by the user agent. This developer-supplied constructor function is called the <dfn id="dfn-custom-element-constructor">custom element constructor</dfn>.</p>
+<p>A <dfn id="dfn-custom-element">custom element</dfn> is an <a href="https://dom.spec.whatwg.org/#concept-element">element</a> that is <a>custom</a>. Informally, this means that its constructor and prototype are defined by the author, instead of by the user agent. This author-supplied constructor function is called the <dfn id="dfn-custom-element-constructor">custom element constructor</dfn>.</p>
 
 <p>Two distinct types of <a lt="custom element">custom elements</a> can be registered:</p>