docs: Crypto Cipher and Decipher examples use deprecated createCipher and createDecipher

[mayankasthana]

The examples at
https://github.com/nodejs/node/blob/v11.1.0/doc/api/crypto.md#class-cipher

const cipher = crypto.createCipher('aes192', 'a password');

and

https://github.com/nodejs/node/blob/v11.1.0/doc/api/crypto.md#class-decipher

const decipher = crypto.createDecipher('aes192', 'a password');

use deprecated methods crypto.createCipher() and crypto.createDecipher().

The examples should be updated to use crypto.createCipheriv() and crypto.createDecipheriv() instead.

[aduh95]

@mayankasthana Do you want to submit a PR to fix that?

[mayankasthana]

Sure!