The wikimedia wiki is used for documentation and discussion on the topic of running a wiki, and on specifically running MediaWiki (the underlying software that powers these sites).
Since this is an article about a topic relevant to running wikis, it's on the meta wiki. It is unlikely to be notable enough to meet the criteria for being included in Wikipedia; in order to avoid everyone creating their own personal Wikipedia page or a Wikipedia page for their high school band or the like, which can be very hard to ensure is high quality and accurate, Wikipedia has notability and verifiability requirements. Something must be notable enough to have been published by several existing reputable sources in order to meet this guideline.
It's fairly likely that Cunningham's Law does not meet those criteria. But the Wikimedia meta-wiki has less formal requirements, and its topic is explicitly discussion about running wikis, so this winds up there.
If you click on the logo, you can see this described straight from the source: https://meta.wikimedia.org/wiki/Main_Page
"Welcome to Meta-Wiki, the global community site for the Wikimedia projects and the Wikimedia movement in general. Meta-Wiki's discussions range from coordination and documentation to planning and analysis of future Wikimedia activities."