Update the no-proto rule documentation

[fasttime]

The version of ESLint you are using.

5.16.0.

The problem you want to solve.

The documentation of the no-proto rule seems to be outdated as of today. I can point out three issues:

• The documentation only suggests using getPrototypeOf method instead of __proto__. But getPrototypeOf cannot change the prototype of an object, and as such cannot be used to rewrite assignments to the __proto__ property, which the no-proto rule complains about.
• The documentation says that "support for getPrototypeOf is not yet universal". Now getPrototypeOf (unlike setPrototypeOf) is part of ES 5.1 spec and is implemented in browsers as old as IE 9 and Safari 7.
• There are two choices for getPrototypeOf: Object.get​PrototypeOf and Reflect​.getPrototypeOf, where the main difference is browser support. The documentation leaves this ambiguity open to the reader.

Your take on the correct solution to problem.

I'd be glad to submit a PR if the team agrees that the rule documentation needs to be updated.

Are you willing to submit a pull request to implement this change?

Sure.

[platinumazure]

Hi @fasttime, thanks for the issue!

This sounds like a reasonable and useful documentation improvement to me, and I would love to see a pull request!