fix: tidy up fetch init with request example

[bsmth]

Description:

There's a couple of improvements here to get rid of redundant code for the GET request. I believe the method, mode and cache properties are all defaults, so I'm leaving the headers as something a reader is likely to customize with auth, or caching, or something custom.

No real preference on the following:

const req = new Request("flowers.jpg", options);
fetch(req)

vs

const req = new Request("flowers.jpg");
fetch(req, options)

Fixes #151

Related issues and pull requests:

• TODO content PR

[bsmth]

Thank you!