Update configuration change section

[beaufortfrancois]

Based on #83 and #80 discussions, this PR improves the status quo of the configuration change section with this changes:

• Fire the configurationchange event only if capabilities and settings differ
• Add a JavaScript example
• Define the configurationchange event handler event type

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Preview | Diff

[jan-ivar]

Thanks for adding more algorithms! Unfortunately, it raises some questions which I've filed as #90.

[beaufortfrancois]

Your feedback has been addressed.

[beaufortfrancois]

Shall we merge?

[jan-ivar]

Editors can integrate once @eladalon1983 has looked at it.

[eladalon1983]

nit: It's weird to see the </pre> as less indented than the </div>. The following indentation seems preferrable imho:

    <h3>Example</h3>
    <div>
      <p>This example shows how to monitor external background blur changes.</p>
      <pre class="example">
       const stream = await navigator.mediaDevices.getUserMedia({video: true});
       const [track] = stream.getVideoTracks();
       let {backgroundBlur} = track.getSettings();
       applyBlurInSoftwareInstead(!backgroundBlur);

       track.addEventListener("configurationchange", () => {
         if (backgroundBlur != track.getSettings().backgroundBlur) {
           backgroundBlur = track.getSettings().backgroundBlur;
           applyBlurInSoftwareInstead(!backgroundBlur);
         }
       });
      </pre>
    </div>
  </section>

[beaufortfrancois]

Fixed in 3e48bd2