Improve docs regarding Crypt defaults

[elcreator]

1. Defaults are cipher = Crypt::DEFAULT_CIPHER, bool useSigning = true, and according to IDE stubs DEFAULT_CIPHER is aes-256-cfb padFactory = null. It should be clear from the docs - will it be changed or not in near releases as it's crucial to not change it accidentally on update otherwise users will lose their data.
2. According to current docs aes-256-cfb is selected by default. The aes-256-gcm is the preferable cipher. If aes-256-gcm is preferrable, maybe it worth to use it in docs in cipher setting examples?
3. Now docs say ->setCipher('aes256') - is it correct value? Also we need setHashAlgorithm parameter values, at least state that default value is
   DEFAULT_ALGORITHM = 'sha256'

https://github.com/phalcon/documentation/edit/master/docs/encryption-crypt.md

[elcreator]

Also consider using https://en.wikipedia.org/wiki/ChaCha20-Poly1305 as it's faster, better prone to Spectre attacks and is recommended mode according to current PHP docs https://www.php.net/manual/en/function.sodium-crypto-aead-xchacha20poly1305-ietf-encrypt.php