README: apply gofmt to examples

[alexandear]

Summary

Format Go code in the README with gofmt and remove empty lines.

Changes

• Replace spaces with tabs.
• Add empty lines between imports.
• Remove empty lines in blocks.

Motivation

The code should be formatted the same as gofmt even in the documentation.

[dolmen]

It would be helpful to have a CI test that ensures this remains in the future. Any pointer to such a tool that would extract blocks of go code from a Markdown document and report diffs?

[ccoVeille]

I'm using mdsf for formatting fenced blocks in Markdown files.

https://github.com/hougesen/mdsf