doc: add code example to process.throwDeprecation property

[juanarbol]

Checklist

• documentation is changed or added
• commit message follows commit guidelines

[jasnell]

It may be worthwhile to include an example that shows process.throwDeprecation is mutable at runtime...

process.throwDeprecation = true;

process.emitWarning('test', 'DeprecationWarning');
// will cause an error to be thrown

[juanarbol]

Totally worth it!

[juanarbol]

Should docs change? I mean, may say that process. throwDeprecation is mutable at runtime like: "The process.throwDeprecation is a mutable property at runtime which indicates...". And of course, add your example

[jasnell]

That would be good, I think

[danbev]

CI-lite: https://ci.nodejs.org/job/node-test-pull-request-lite-pipeline/3903/

[Trott]

This text is a little confusing.

• It's not clear what the difference between "mutable property at runtime" vs. "mutable property" would be. I don't think there is any in this case.
• Since it is mutable, it doesn't necessarily indicate whether the command line flag is set.

Maybe something more like this?

The initial value of `process.throwDeprecation` indicates whether the 
`--throw-deprecation` flag is set on the current Node.js process. See
the documentation for the [`'warning'` event][process_warning] and the
[`emitWarning()` method][process_emit_warning] for more information.
`process.throwDeprecation` is mutable, so whether or not deprecation
warnings results in an error may be altered at runtime. 

[juanarbol]

Yeap, that's quite confusing.

Your proposal seems to be more clear than mine (on my opinion), but on my reading experience, I think is quite better switch the order of the sentences about process.throwDeprecation property and emitWarning() and warning event, to make that paragraph with a little bit more of cohesion.

Fixed on bf3bcf7.

[Trott]

I'd like to see the text edited a bit more before landing.

[Trott]

Suggested change

	`--throw-deprecation` flag is set on the current Node.js process,
	`--throw-deprecation` flag is set on the current Node.js process.

[Trott]

Suggested change

	warnings results in an error may be altered at runtime. See the
	warnings result in errors may be altered at runtime. See the

[juanarbol]

@Trott, Thanks! Fixed on a6d19ba

thanks for editing!

[Trott]

Lite CI: https://ci.nodejs.org/job/node-test-pull-request-lite-pipeline/3923/

[Trott]

Landed in 68d6c4c