A static page that hosts documentation on an internal network does not need encryption.
The added overhead of certificate maintenance (and investigating when it does and will break) is simply not worth the added cost.
Of course the workaround most shops do nowadays is just hide the HTTP servers behind a load balancer doing SSL termination with a wildcard cert. An added layer of complexity (and now single point of failure) just to appease the WebPKI crybabies.