DOC: API: add render helper examples

Let's add an example usage of all of the render helpers (render, clearRender)
to the API docs.

(cherry picked from commit fb7d293)

(cherry picked from commit 0dfb1dc)

API.md

@@ -311,7 +311,7 @@ keyboard.
 
 #### Parameters
 
-*   `options` **[Object][72]?** optional tab behaviors (optional, default `{}`)
+*   `options` **[Object][72]?** optional tab behaviors
 
     *   `options.backwards` **[boolean][71]** indicates if the the user navigates backwards (optional, default `false`)
     *   `options.unRestrainTabIndex` **[boolean][71]** indicates if tabbing should throw an error when tabindex is greater than 0 (optional, default `false`)
@@ -574,6 +574,14 @@ Renders the provided template and appends it to the DOM.
 *   `templateOrComponent` **(Template | Component)** the component (or template) to render
 *   `options` **RenderOptions** options hash containing engine owner ({ owner: engineOwner })
 
+#### Examples
+
+Render a div element with the class 'container'.
+
+```javascript
+await render(hbs`<div class="container"></div>`);
+```
+
 Returns **[Promise][66]\<void>** resolves when settled
 
 ### clearRender
@@ -883,6 +891,17 @@ element).
 
 *   `context` **TestContext** the context to setup for rendering
 
+#### Examples
+
+Rendering out a paragraph element containing the content 'hello', and then clearing that content via clearRender.
+
+```javascript
+await render(hbs`<p>Hello!</p>`);
+assert.equal(this.element.textContent, 'Hello!', 'has rendered content');
+await clearRender();
+assert.equal(this.element.textContent, '', 'has rendered content');
+```
+
 Returns **[Promise][66]\<RenderingTestContext>** resolves with the context that was setup
 
 ### getApplication
@@ -1241,23 +1260,23 @@ Returns **([Array][70]\<Warning> | [Promise][66]<[Array][70]\<Warning>>)** An ar
 
 [54]: #getdeprecations
 
-[55]: #examples-22
+[55]: #examples-24
 
 [56]: #getdeprecationsduringcallback
 
 [57]: #parameters-29
 
-[58]: #examples-23
+[58]: #examples-25
 
 [59]: #getwarnings
 
-[60]: #examples-24
+[60]: #examples-26
 
 [61]: #getwarningsduringcallback
 
 [62]: #parameters-30
 
-[63]: #examples-25
+[63]: #examples-27
 
 [64]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
 

addon-test-support/@ember/test-helpers/setup-rendering-context.ts

@@ -91,6 +91,12 @@ export interface RenderOptions {
   @param {Template|Component} templateOrComponent the component (or template) to render
   @param {RenderOptions} options options hash containing engine owner ({ owner: engineOwner })
   @returns {Promise<void>} resolves when settled
+
+  @example
+  <caption>
+    Render a div element with the class 'container'.
+  </caption>
+  await render(hbs`<div class="container"></div>`);
 */
 export function render(
   templateOrComponent: TemplateFactory | ComponentInstance,
@@ -270,6 +276,16 @@ export function clearRender(): Promise<void> {
   @public
   @param {TestContext} context the context to setup for rendering
   @returns {Promise<RenderingTestContext>} resolves with the context that was setup
+
+  @example
+  <caption>
+    Rendering out a paragraph element containing the content 'hello', and then clearing that content via clearRender.
+  </caption>
+
+  await render(hbs`<p>Hello!</p>`);
+  assert.equal(this.element.textContent, 'Hello!', 'has rendered content');
+  await clearRender();
+  assert.equal(this.element.textContent, '', 'has rendered content');
 */
 export default function setupRenderingContext(
   context: TestContext