Specs and Docs: minor updates to fix mistakes I found when proof-reading

sky/examples/style/hex-layout.sky

 #!mojo mojo:sky
 <import src="sky:core" as="sky"/>
 <script>
  class BeehiveLayoutManager extends sky.LayoutManager {
    function layout(width, height) {
      this.markAsLaidOut();
      if (width == null)
        width = this.getIntrinsicWidth().value;
      let autoHeight = false;
      if (height == null) {
@@ skipping 97 matching lines @@
      while (!loop.done) {
        let child = loop.value;
        if (this.inHex(child.x, child.y, child.width, child.height, x, y))
          return child.layoutManager.hitTest(x-child.x, y-child.y);
        loop = children.next();
      }
      return this.node;
    }
  }
  sky.registerLayoutManager('beehive', BeehiveLayoutManager);
- let BeehiveCountStyleValueType = new StyleValueType();
- BeehiveCountStyleValueType.addParser((tokens) => {
+ let BeehiveCountStyleGrammar = new StyleGrammar();
+ BeehiveCountStyleGrammar.addParser((tokens) => {
    let token = tokens.next();
    if (token.done)
      throw new Error();
    if (token.value.kind != 'number')
      throw new Error();
    if (token.value.value <= 0)
      throw new Error();
    if (Math.trunc(token.value.value) != token.value.value) // is integer
      throw new Error();
-   return {
-     value: token.value.value;
-   }
+   return new NumericStyleValue(token.value.value);
  });
  sky.registerProperty({
    name: 'beehive-count',
-   type: BeehiveCountStyleValueType,
+   type: BeehiveCountStyleGrammar,
    inherits: true,
    initialValue: 5,
    needsLayout: true,
  });
 </script>
 <style>
  div { display: beehive; beehive-count: 3; }
 </style>
 <div>
  <t>Hello</t>
  <t>World</t>
  <t>How</t>
  <t>Are</t>
  <t>You</t>
  <t>Today?</t>
 </div>