Document `mode="continuous"`

[JonnyBurger]

It seems like there is no mention of this prop at all in the docs.

[chrfalch]

This is hopefully a property that shouldn't be necessary but one that we've used for debugging in development - our goal is that there should never be any need for a continuous mode - that all the reactive re-rendering will happen automatically (we are basically done with this) - so this property will hopefully be deprecated in the near future.

[wcandillon]

@chrfalch I updated the PR in a way that matches your comment.