ClickHouse is an open-source project developed on GitHub. As customary, contribution instructions are published in CONTRIBUTING file in the root of the source code repository.
We can refer to systems like MapReduce as distributed computing systems in which the reduce operation is based on distributed sorting. The most common open-source solution in this class is Apache Hadoop.
Being an open-source product makes this question not so straightforward to answer. You do not have to tell anyone if you want to start using ClickHouse, you just go grab source code or pre-compiled packages.