Github clone URLs need to be updated since Github dropped git:// protocol

Github dropped support of git:// protocol while cloning repositories. More info at https://github.blog/changelog/2022-03-15-removed-unencrypted-git-protocol-and-certain-ssh-keys/

Given that, there (at wildfly projects) are code snippets (where git:// is used) which should be updated:

• ./docs/src/main/asciidoc/_hacking/github_setup.adoc:git remote add upstream git://github.com/wildfly/wildfly.git
  ./docs/src/main/asciidoc/_hacking/github_setup.adoc:From git://github.com/wildfly/wildfly
  ./docs/src/main/asciidoc/_high-availability/Clustering_and_Domain_Setup_Walkthrough.adoc:git clone git://github.com/liweinan/cluster-demo.git