Add pause before play feature information to documentation/featurelist/wiki

The hold play button to allow the audio player to pause for a bit before starting is not documented and hence will not be known by users. We need to either document this, or add an introductory how-to explanation for all screens within the app.

Start with `documentation/featurelist/wiki` and any docs index/README links to locate where player controls are described. Read the existing how-to or feature-list text for the audio player and add a clear note about the hold-play pause-before-start behavior. Consider whether the change should be a short entry in the feature list or a broader how-to section across screens, and mark the issue done when the documentation explicitly explains this behavior in user-facing docs; no code tests are implied.

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