Fix broken link in issue template (#4323)

Fixes #4222

.github/ISSUE_TEMPLATE/feature-request.md

@@ -1,6 +1,6 @@
 ---
 name: 🚀 Feature Request
-about: Feature requests are managed in the Apollo Feature Request repo (https://github.com/apollographql/apollo-feature-request).
+about: Feature requests are managed in the Apollo Feature Request repo (https://github.com/apollographql/apollo-feature-requests).
 ---
 
 Thanks for your interest in helping make Apollo Client better!