docs: Improve code examples

[coalooball]

See https://github.com/duesee/imap-codec/issues/393

[coalooball]

Also see https://github.com/duesee/imap-codec/issues/394

[duesee]

Hehe, I was just about to merge because I overlooked https://github.com/duesee/imap-codec/pull/397/files#diff-cfcb5beb66760b7d974ea036d027714665a3c57f72ca940df6dcdd3e138a1d69R24-R32 :D Good that we have a CI :-) I think it should be enough to remove this? Same with https://github.com/duesee/imap-codec/pull/397/files#diff-cfcb5beb66760b7d974ea036d027714665a3c57f72ca940df6dcdd3e138a1d69R65-R72? Maybe also toss a cargo +nightly fmt just in case.

[coalooball]

Whoops (○´･д･)ﾉ my bad, I didn't use cargo t to test. Thought the code below was a no-go:

//! # use imap_codec::{
//! # encode::Encoder,
//! # imap_types::{
//! # core::Text,
//! # response::{Code, Greeting, GreetingKind},
//! # },
//! # GreetingCodec,
//! # };

I originally wanted to write a separate section to specifically explain how to use imap-types, but I thought it would be better to write it as a comment in the code, so I deleted your previous code. Now, cargo t aced the test. The CI is my lifesaver!

[coveralls]

Pull Request Test Coverage Report for Build 7130307555

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 92.448%

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Totals
Change from base Build 7129545557:	0.0%
Covered Lines:	8728
Relevant Lines:	9441

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💛 - Coveralls

[duesee]

Thanks! :-)

[duesee]

Oh, btw @coalooball: Was this your first PR on GitHub? I feel honored! :D Congratz 🎉

[coalooball]

Haha, this is my first PR, and I'm pretty excited about it. Thank you for your blessings, @duesee! I hope I can become as awesome as you, contributing real-code PRs to imap-codec.