URL Cleanup

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://beanvalidation.org/ with 1 occurrences migrated to:
  https://beanvalidation.org/ ([https](https://beanvalidation.org/) result 200).
* [ ] http://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/ with 1 occurrences migrated to:
  https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/ ([https](https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/) result 200).
* [ ] http://github.com/spring-projects/spring-shell with 1 occurrences migrated to:
  https://github.com/spring-projects/spring-shell ([https](https://github.com/spring-projects/spring-shell) result 200).
* [ ] http://start.spring.io with 2 occurrences migrated to:
  https://start.spring.io ([https](https://start.spring.io) result 200).
* [ ] http://www.java.com/en/download/help/error_hotspot.xml with 1 occurrences migrated to:
  https://www.java.com/en/download/help/error_hotspot.xml ([https](https://www.java.com/en/download/help/error_hotspot.xml) result 200).
* [ ] http://contributor-covenant.org with 1 occurrences migrated to:
  https://contributor-covenant.org ([https](https://contributor-covenant.org) result 301).
* [ ] http://contributor-covenant.org/version/1/3/0/ with 1 occurrences migrated to:
  https://contributor-covenant.org/version/1/3/0/ ([https](https://contributor-covenant.org/version/1/3/0/) result 301).

spring-shell-test-samples/.gitignore

@@ -115,7 +115,7 @@ xcuserdata/
 *.war
 *.ear
 
-# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+# virtual machine crash logs, see https://www.java.com/en/download/help/error_hotspot.xml
 hs_err_pid*
 
 ## Eclipse