fix for #6558 default value will not be passed through validated_data

[samims]

Change docs. It was saying default date value on serializer will be passed through validated data if date field is set to read_only=True which was clearly not passing.

[carltongibson]

This is right. The comment was obviously missed when the behaviour was altered here. (Was it v3.8?)

Except for being explicit, not sure we need the test: it should already be covered... (?)

[samims]

Is there anything I need to change? Can you please let me know?

[rpkilby]

Thanks for the ping. Forgot to check in on this issue. Does this only affect date fields, or any fields with read_only+default?

[carltongibson]

The behaviour was changed for all field types. (The change here looks clearly right to me. I probably should have just merged it already...)

[carltongibson]

Oh, except I’m not sure if we need the test of not. What do people think? (Can’t hurt I guess...)

[rpkilby]

I've created a new PR for just the docs change.