docs: "Serving": more consistent examples

[aghArdeshir]

It became distracting at some point when examples changed from my-domain.dev to my-domain.com This page includes 10 examples, 7 of them are my-domain.com and 3 of them are my-domain.dev. I made them more consistent.

target page: https://modern-web.dev/guides/going-buildless/serving/

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Latest commit: 71260f9

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