Add more documentation on usage as a Go library

[ashishb]

Consider https://daseldocs.tomwright.me/examples/change-file-format it talks about how to use dasel as a binary to transform one file format to another.

Please consider adding some examples on how to do the same while using dasel as a library.

[TomWright]

I've deleted the comment above because of safety concerns. It contained a phishing/malicious link.