remove `/` from copy sku files url

[julia-rabello]

EDU-12476

Types of changes

• [ ] New content (endpoints, descriptions or fields from scratch)
• [ ] Improvement (make an endpoint's title or description even better)
• [x] Spelling and grammar accuracy (self-explanatory)

Changelog

Do not forget to update your changes to our Developer Portal's changelog. Did you create a release note?

• [ ] Yes, I already created a release note about this change.
• [x] No, but I am going to.

[github-actions[bot]]

Thanks for your contribution. The .json file will be checked now with Spectral.