Link broken:

In the OpenStack Cloud Software section, the following hyperlink is broken: The hardware requirements document specifies the minimum requirements.

Below is the section where the broken link lives. It's the very last sentence in the provided excerpt below.

Planning an installation
Before deploying any services, it is very useful to take stock of the resources available and how they are to be used. OpenStack comprises of a number of interrelated services (Nova, Swift, etc) which each have differing demands in terms of hosts. For example, the Swift service, which provides object storage, has a different requirement than the Nova service, which provides compute resources.

The minimum requirements for each service and recommendations are laid out in the official OpenStack Operations Guide which is available (free) in HTML or various downloadable formats. The hardware requirements document specifies the minimum requirements.