CRM-11658 - releaser - Explain why there are two git_base_url options

tools/scripts/releaser/releaser.conf.txt

 #!/bin/bash
 
 ## The GIT repo where we can find branches and create tags
+## Note: Choose https or SSH depending on whether you've
+## configured HTTP credential cache or SSH keys.
 #git_base_url=https://github.com/civicrm
 #git_base_url=git@github.com:civicrm