Description for content of dialogs

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Description would be improved by providing a description of the content in the following dialogs:

• Transitions dialog (TransitionsDialog.ts) - not actually a Dialog, using a Panel to fake a non-modal Dialog
• Quantum Numbers info dialog (QuantumNumbersInfoDialog.ts)
• Oops dialog (ExperimentOopsDialog.ts)

As previously decided in MOTHA description design meetings, this will not be addressed in the 1.0 release, and is deferred to a future release.

For TransitionsDialog, it would be preferrable to address phetsims/sun#916 (Create a non-modal dialog) so that we can use the Dialog API for description, and not have to fake it.