Remove out of date C++ client docs

Someone pointed me to the following documentation page:

http://infinispan.org/docs/hotrod-clients/cpp/

It has an error in the source code, but it is not in the documentation subdirectory of the infinispan project source tree. I could not find the text included in this page in the current documentation either. This set of docs needs to be removed from the website, and then this documentation needs to be folded into the current documentation set.