Contribute a small example for how to use SockAddrStorage::view_as

[shaun-cox]

In order to help demonstrate how to create a SockAddr from an instance of a libc::sockaddr_storage, @Thomasdezeeuw proposed adding an example in #613.

I also took the liberty of addressing a few markdownlint items in the readme and contributing docs... Hope that was okay.

[Thomasdezeeuw]

Example LGTM

[Darksonn]

I'm pretty sure dead-code warnings are disabled by default in documentation tests.

[shaun-cox]

@Darksonn, I'm running cargo test --all-features locally and seeing this (without the allow(dead_code))

---- src/sockaddr.rs - sockaddr::SockAddrStorage::view_as (line 54) stdout ----
error: function `from_sockaddr_storage` is never used
 --> src/sockaddr.rs:60:4
  |
9 | fn from_sockaddr_storage(recv_address: &sockaddr_storage) -> SockAddr {
  |    ^^^^^^^^^^^^^^^^^^^^^
  |
note: the lint level is defined here
 --> src/sockaddr.rs:52:9
  |
1 | #![deny(warnings)]
  |         ^^^^^^^^
  = note: `#[deny(dead_code)]` implied by `#[deny(warnings)]`

error: aborting due to 1 previous error

Couldn't compile the test.

Do I possibly have something misconfigured locally to cause this?

[Darksonn]

Oh, there is a #![doc(test(attr(deny(warnings))))] in socket2. I didn't know about that. It's because of that.

[Thomasdezeeuw]

Thanks @shaun-cox, I'll sort out the CI another pr.

[Thomasdezeeuw]

@shaun-cox can you rebase the pr? It should fix the CI issues