docs(gatsby-link): add example of passing state

[GarrettJMU]

Update docs to show how state is passed through the location object.

[jgierer12]

Some changes for better syntax highlighting ✨

Please also make sure to format this file with Prettier.

[GarrettJMU]

@jgierer12 updated the copy. Good call, much better read now.

[jgierer12]

Thank you! Please also download Prettier and use it to format the file, that will get rid of the failing CI too 😉

[GarrettJMU]

@jgierer12 should pass now.

[pieh]

Thanks @GarrettJMU and @jgierer12!

[gatsbot]

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