docs: internationalize & replace jargon in vpn-latency-explained.md

[getsnoopy]

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[getsnoopy]

@rapenne-s Impact means "crash force", which makes no sense in the documentation. It has a proscribed, jargon sense of "strong/violent/marked effect", which—ignoring the fact that it's proscribed and jargon—still doesn't make sense in the documentation. For example, the first phrase would read "speed performance strong/violent/marked effect", which is a leading statement, since one doesn't know that VPNs have such a strong effect on speed performance.

Secondly, the change from "kilometers" to kilometres is not a "US to UK spelling" change; kilometres is the official, international spelling of the word in English as outlined in the SI (modern metric system). You can see this on the BIPM's official website.

Finally, as for the words that actually have been changed from the US standard to the UK ones, the rest of your website/documentation follows British spelling (as it should, since you're based in France and are targeting a global audience).