switch all maven repository URLs to HTTPS

Author: stefanseifert

public_site/src/site/markdown/maven.md

@@ -4,7 +4,7 @@
 
 The released wcm.io artifacts are available at Maven Central:
 
-http://search.maven.org/#search|ga|1|io.wcm.devops
+https://search.maven.org/search?q=io.wcm.devops
 
 Snapshots releases are available on the Sonatype snapshot repository - use at your own risk!