views/xmlrpc: Add documentation for API methods

views/xmlrpc: Add documentation for API methods

This will be useful for populating the XML-RPC API documentation.

Note that this uses the Google-style docstring format. This format is
easier to read than the information-dense, "classic" Sphinx docstring
format making it more suitable for use with pydoc (which does not do
any post-processing and it used by the 'DocXMLRPCServer' module). If
generating documentation using Sphinx, this will require the usage of
the 'sphinx.ext.napoleon' extension.

Signed-off-by: Stephen Finucane <stephen.finucane@intel.com>