URL Cleanup (#4)

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://www.h2database.com with 1 occurrences migrated to:
  https://www.h2database.com ([https](https://www.h2database.com) 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).

# Ignored
These URLs were intentionally ignored.

* http://localhost:8080 with 1 occurrences

CODE_OF_CONDUCT.adoc

@@ -40,5 +40,5 @@ appropriate to the circumstances. Maintainers are obligated to maintain confiden
 with regard to the reporter of an incident.
 
 This Code of Conduct is adapted from the
-http://contributor-covenant.org[Contributor Covenant], version 1.3.0, available at
-http://contributor-covenant.org/version/1/3/0/[contributor-covenant.org/version/1/3/0/]
+https://contributor-covenant.org[Contributor Covenant], version 1.3.0, available at
+https://contributor-covenant.org/version/1/3/0/[contributor-covenant.org/version/1/3/0/]

documentation.adoc

@@ -18,7 +18,7 @@ application ends.
 TIP: The "`How-to`" section includes a <<howto.adoc#howto-database-initialization,
 section on how to initialize a database>>.
 
-Spring Boot can auto-configure embedded http://www.h2database.com[H2],
+Spring Boot can auto-configure embedded https://www.h2database.com[H2],
 for reactive usage. You need not provide any connection URLs.
 You need only include a build dependency to the embedded database that you want to use.