Update adding or removing extensions procedure

[svor]

What does this pull request change?

Update adding or removing VS Code extensions procedure

Related MR: https://gitlab.cee.redhat.com/red-hat-developers-documentation/devspaces-documentation/-/merge_requests/83

What issues does this pull request fix or reference?

https://issues.redhat.com/browse/CRW-6542

Specify the version of the product this pull request applies to

Pull Request checklist

The author and the reviewers validate the content of this pull request with the following checklist, in addition to the automated tests.

• Any procedure:
  • [ ] Successfully tested.
• Any page or link rename:
  • [ ] The page contains a redirection for the previous URL.
  • Propagate the URL change in:
    • [ ] Dashboard default branding data
• [ ] Builds on Eclipse Che hosted by Red Hat.
• [ ] the Validate language on files added or modified step reports no vale warnings.

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[ibuziuk]

@deerskindoll please, back port for 3.15 once merged

[svor]

Converted to draft, I'm going to add more information

[svor]

@deerskindoll PR is ready for review