add resize doc

docs/layout/resize.md

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+# Layout: resize
+
+`resize` is a helper function that provides a way to set the size of a chart, or other content, to fit into a container on your page.
+
+`resize` takes a function that renders content, like a chart.  When the page is rendered, `resize` calls the render function with the **width** and, optionally the **height**, of its parent container.  If the page changes size, `resize` calls your function again with the new **width** and **height** values that re-renders the content to fit in the newly resized page.
+
+## Width only
+
+If your content defines its own height then only use the `width` parameter:
+
+```js
+html`<div class="grid grid-cols-2">
+  <div class="card">
+    ${resize((width) => Plot.barY([9, 4, 8, 1, 11, 3, 4, 2, 7, 5]).plot({width, height: 150}))}
+  </div>
+  <div class="card">
+    ${resize((width) => Plot.barY([3, 4, 2, 7, 5, 9, 4, 8, 1, 11]).plot({width, height: 150}))}
+  </div>
+</div>`
+```
+
+```html run=false
+<div class="grid grid-cols-2">
+  <div class="card">
+    ${resize((width) => Plot.barY([9, 4, 8, 1, 11, 3, 4, 2, 7, 5]).plot({width, height: 150}))}
+  </div>
+  <div class="card">
+    ${resize((width) => Plot.barY([3, 4, 2, 7, 5, 9, 4, 8, 1, 11]).plot({width, height: 150}))}
+  </div>
+</div>
+```
+
+## Width and height
+
+If your container defines a height, in this example `300px`, then you can use both the `width` and `height` parameters:
+
+
+```js
+html`<div class="grid grid-cols-2" style="grid-auto-rows: 300px;">
+  <div class="card">
+    ${resize((width, height) => Plot.barY([9, 4, 8, 1, 11, 3, 4, 2, 7, 5]).plot({width, height}))}
+  </div>
+  <div class="card">
+    ${resize((width, height) => Plot.barY([3, 4, 2, 7, 5, 9, 4, 8, 1, 11]).plot({width, height}))}
+  </div>
+</div>`
+```
+
+```html run=false
+<div class="grid grid-cols-2" style="grid-auto-rows: 300px;">
+  <div class="card">
+    ${resize((width, height) => Plot.barY([9, 4, 8, 1, 11, 3, 4, 2, 7, 5]).plot({width, height}))}
+  </div>
+  <div class="card">
+    ${resize((width, height) => Plot.barY([3, 4, 2, 7, 5, 9, 4, 8, 1, 11]).plot({width, height}))}
+  </div>
+</div>
+```
+
+Note: If you are using `resize` with both `width` and `height` and see nothing rendered, it may be because your parent container does not have its own height specified.