Content update: Links component

[natalia-fitzgerald]

This issue is to correct a very small content issue in the links component stories. All stories should be singular. The first few are currently plural.

Current behavior

Expected behavior

Steps to replicate behavior (include URLs)

• Go to: https://cfpb.github.io/design-system-react/?path=/docs/components-verified-links--overview
• Compare to: https://cfpb.github.io/design-system/components/links