[Docs/Website] DataTypes article mentions Interval types

[mwachs5]

Type of issue: Bug Report

Please provide the steps to reproduce the problem:

Look at the website about DataTypes: https://www.chisel-lang.org/chisel3/docs/explanations/data-types.html

What is the current behavior?

It says:

And there is still the article about Interval Type under experimental features: https://www.chisel-lang.org/chisel3/docs/appendix/experimental-features#interval-type

What is the expected behavior?

There should be no mention of IntervalTypes because they are no longer supported.

Source for first issue is here: https://github.com/chipsalliance/chisel/blob/main/docs/src/explanations/data-types.md

Second issue is here: https://github.com/chipsalliance/chisel/blob/main/docs/src/appendix/experimental-features.md

Please tell us about your environment:

Other Information

What is the use case for changing the behavior?

Less user confusion