Docs: Broken hyperlink for "Metaflow Decorators" on GSoC 2026 page

[Sreeram5678]

While reviewing the GSoC 2026 project ideas page, I noticed that the link pointing to "Metaflow Decorators" (https://docs.metaflow.org/api/decorators) returns a 404 error because the documentation architecture has been updated.

I will submit a PR shortly to update this link to the correct current API reference (https://docs.metaflow.org/api/step-decorators).

Edit: I also noticed a second broken link on this same page pointing to the deprecated metaflow_rc repository. I will update this to point to the current metaflow-nflx-extensions repository in the same PR.