Fix `Stack Build` wizard description in koding.md

What does this MR do?

Fixes the language in the Stack Build wizard description.

Are there points in the code the reviewer needs to double check?

The paragraph describing the Stack Build wizard.

Why was this MR needed?

The language contained a phrasing mistake (either allow you to + verb or let you + verb, the second form was chosen)

What are the relevant issue numbers?

No issue was opened, this was spotted while reading the documentation for the Koding integration.

Screenshots (if relevant)

Does not apply.

Does this MR meet the acceptance criteria?

• CHANGELOG entry added Does not apply
• Documentation created/updated Does not apply
• API support added Does not apply
• Tests
  • Added for this feature/bug Does not apply
  • All builds are passing (scoped down to doc lint and license finder)
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together Does not apply