acquit for all guides

[vkarpov15]

No description provided.

[hasezoey]

what exactly is this issue trying to track and what still needs to be done?

(also i think the docs label should be added)

[hasezoey]

what exactly is this issue trying to track and what still needs to be done?

thanks to some more time and #13635, i think i now know the purpose of this issue better, following is a description of what this issue is about and what still needs to be done

---

this issue is tracking that most code examples in the documentation are actually tests and extracted and inserted into the documentation from those tests

example in documentation:

mongoose/docs/promises.md

Lines 13 to 15 in e48aa77

	```acquit
	[require:Built-in Promises]
	```

test example:

mongoose/test/docs/promises.test.js

Lines 34 to 49 in e48aa77

	it('Built-in Promises', function(done) {
	const gnr = new Band({
	name: 'Guns N\' Roses',
	members: ['Axl', 'Slash']
	});
	const promise = gnr.save();
	assert.ok(promise instanceof Promise);
	promise.then(function(doc) {
	assert.equal(doc.name, 'Guns N\' Roses');
	// acquit:ignore:start
	done();
	// acquit:ignore:end
	});
	});

examples of which still need to be transferred:

mongoose/docs/faq.md

Lines 35 to 51 in e48aa77

	```javascript
	await mongoose.createConnection(mongodbUri).asPromise();
	const Test = mongoose.model('Test', schema);
	await Test.findOne(); // Will throw "Operation timed out" error because didn't call `mongoose.connect()`
	```
	```javascript
	await mongoose.connect(mongodbUri);
	const db = mongoose.createConnection();
	const Test = db.model('Test', schema);
	await Test.findOne(); // Will throw "Operation timed out" error because `db` isn't connected to MongoDB
	```

---

some questions regarding some examples:

• what should we do about examples that use const mongoose = require('mongoose'), should we let this be staying in a test, or should we remove those imports OR should we leave that import statement in the codeblock and only insert the acquit insert? (they should be combined to my understanding) example
• the same as the first, what should we do about import ... from "mongoose"?
• should "small" example also be transferred to tests, like one-liners? example