Fix wrong link to GDK in README file

What does this MR do?

Fixes bug of wrong link to GDK in the README file

Why was this MR needed?

Correct documentation navigation :)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #30817 (closed)