Atom collects user metrics

[hroncok]

Based on discussion in #540 it seems that we care about privacy and adding a guide to disable VS Code telemetry was a must.

To be fair, Atom also collects user data, although apparently by free software tooling with limited scope. The collection can be disabled.

We should probably mention this the same way as we did in #540.

[encukou]

To me, the data Atom collects looks reasonable – usage statistics they'd need to prioritize work on the editor.
So I don't see adding opt-out instructions as a blocker. But feel free to add them.