Documentation of FromDataSimple doesn't say it's only for debugging

[malaire]

The documentation of FromDataSimple doesn't mention that it's only for debugging. This is only mentioned at documentation of FromData.

Based on several closed issued about this and recent message at #beginners, this causes enough confusion that documentation of FromDataSimple should also mention this.

[jebrosen]

The documentation of FromDataSimple doesn't mention that it's only for debugging.

FromDataSimple is not only for debugging. The implementations for String and Vec<u8> are only for debugging, and it's a coincidence that they both implement FromDataSimple instead of FromData directly.

I guess we could copy the explanation to the page for FromDataSimple, but I would personally rather remove those implementations entirely in favor of an approach like #990.

[SergioBenitez]

Closing as invalid. I agree that we should expose safer, harder-to-lead-to-DoS APIs for Data. I would also like to rename FromDataSimple to FromData, and FromData to FromTransformedData, to better explain the differences.