Add explicit site URL to resolve site generation issues on GitHub side.

Author: jpsacha

_config.yml

@@ -18,7 +18,7 @@ email: jpsacha@gmail.com
 description: >- # this means to ignore newlines until "baseurl:"
   The ImageJ Plugins project is a source of custom plugins for the ImageJ software package.
 baseurl: "" # the subpath of your site, e.g. /blog
-url: "" # the base hostname & protocol for your site, e.g. http://example.com
+url: "https://ij-plugins.github.io/" # the base hostname & protocol for your site, e.g. http://example.com
 github_username:  ij-plugins
 
 # Build settings