Document cbc tools and their installation instructions

cbc, cbc-pillowfight, cbc-n1qlback are useful tool for Couchbase testing and benchmarking.

Currently they are mentioned between the lines in the documentation of various versions of C SDK. Also the documentation of some of the C SDK versions mention that they can be installed by installing libcouchbase2-bin package.

I did not find any mentioning of these tools and their installation instructions in the latest version of the documentation of C SDK 2.10.

We should follow a consistent strategy of documenting these tools throughout all versions of C SDK, or even consider including them into in the server documentation (e.g. as part of CLI reference). In any case having a separate page for documentation of these tools and their installation instructions would be helpful.