m.call.answer sample has an invalid field.

[Dominaezzz]

Link to problem area:
See the lifetime field here,
https://github.com/matrix-org/matrix-doc/blob/8d9a67d9f64c51be3e8465d7db1f1de5f47faa7a/data/event-schemas/examples/m.call.answer.yaml#L4-L12
it's not actually in the schema.
https://github.com/matrix-org/matrix-doc/blob/8d9a67d9f64c51be3e8465d7db1f1de5f47faa7a/data/event-schemas/schema/m.call.answer.yaml#L8-L38

Issue

Correct the sample or the schema.

[KitsuneRal]

Ftr, after checking across a couple of Element implementations: lifetime seems to be an accidental entry in the example and should not be a part of the specced event content. It's also pretty hard to devise why it would be needed in an answer event even in theory.