Adapt remaining `arcticicestudio` "fade-out" changes

[svengreb]

With the retirement of the Arctic Ice Studio personal & Nord project brand various migrations to the svengreb GitHub account of other projects were also completed within the last weeks. There are also changes in Nord projects like nordtheme/web that other projects depended on and can now be adapted as well.
Therefore all Nord projects must adapt these changes which includes…

• the migration and repository name change of arcticicestudio/nord-docs — all references must be updated.
• the migration of the arcticicestudio/styleguide-git repository to the svengreb real-in-person identity — all references and used npm packages must be updated.
• the migration of the arcticicestudio/styleguide-javascript repository to the svengreb real-in-person identity — all references and used npm packages must be updated.
• the migration of the arcticicestudio/styleguide-markdown repository to the svengreb real-in-person identity — all references and used npm packages must be updated.