Generate API documentation using DocFx via build system.

DocFx is an open source, multiple platform (Win, Macos, Linux) code source documentation generator which is a vast improvement over the much older Sandcastle project which is Windows only.

This story is to integrate DocFx into the Jenkins release build pipeline so that API documentation can done automatically as part of a release.

Once generated, the documentation should be immediately uploaded to S3 (docs.couchbase.com/sdk-api/...) under a directory with the following naming convention: couchbase-net-client-X.Y.Z where X is the major, Y is the minor and Z is the patch. Read permissions will need to be set here as well on the entire directory.

This is created as a story, because there are several steps that make up a complete solution and sub-tasks can be created as appropriate.