Added documentation

[hgrahamcs]

The documentation in docs.rs for escposify is lacking. I've added another example using std::fs::File to improve clarity as well as added usage examples to device::File::from() and printer::Printer.

[TheWaWaR]

Please see how to write doc first.

https://doc.rust-lang.org/rustdoc/how-to-write-documentation.html https://doc.rust-lang.org/rust-by-example/meta/doc.html

[hgrahamcs]

Would you prefer line comments instead of block comments for documentation?

[TheWaWaR]

Would you prefer line comments instead of block comments for documentation?

Yes. Because all my projects use line comments.

[hgrahamcs]

Changed in 9fa0f95.

[ipetrovbg]

This line saved me a lot of troubles under Linux.

File::options().append(true).open("/dev/usb/lp0").unwrap();

[hgrahamcs]

I'm glad I could help!

[hgrahamcs]

@TheWaWaR any progress on reviewing this PR?

[hgrahamcs]

Do we need to bump to 0.5.2?

[TheWaWaR]

Yes, we should.

[hgrahamcs]

13 has a bump