This commit updates URLs to prefer the https protocol. Redirects are not followed to avoid accidentally expanding intentionally shortened URLs (i.e. if using a URL shortener).

# Fixed URLs

## Fixed Success
These URLs were switched to an https URL with a 2xx status. While the status was successful, your review is still recommended.

* [ ] http://spring.io/projects/spring-framework with 4 occurrences migrated to:
  https://spring.io/projects/spring-framework ([https](https://spring.io/projects/spring-framework) result 200).