The source for the project website (http://flink.apache.org/) is located at https://github.com/apache/flink-web.
The website is regenerated nightly using buildbot.
The status of the buildbot builds can be seen at https://ci.apache.org/builders.
There is one buildbot for each release ("flink-docs-release-X.Y") and one for master ("flink-docs-master").
The builds use a shared build script located at https://svn.apache.org/repos/infra/infrastructure/buildbot/aegis/buildmaster/master1/projects/flink.conf that is access via SVN.