fix(simple-data-fetch): add machine context

[timdeschryver]

I copy-pasted the simple-data-fetch example, but the context wasn't updated after a data fetch with the warning Warning: Attempting to update undefined context. This change adds an initial context to the machine, so it's "copy-pastable".

Also, since I got the opportunity now... Thanks for these awesome examples 👍

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[mattpocock]

@all-contributors please add @timdeschryver for code

[allcontributors[bot]]

@mattpocock

I've put up a pull request to add @timdeschryver! :tada:

[mattpocock]

Thanks for the fix!