This patch provides Tacker documents for multi-version API support.
VNF LCM API Version 2 is added to API Reference and the page hierarchy
is changed for readability.
Also, the Show VNF LCM Versions command is added to Command-Line
Interface Reference.
Furthermore, a manual of the Userdata script is added to Tacker User
Guide.
Implements: blueprint multi-version-api
Implements: blueprint support-nfv-solv3-start-and-terminate-vnf
Implements: blueprint support-nfv-solv3-query-vnf-instances
Implements: blueprint support-nfv-solv3-query-operation-occurrences
Implements: blueprint support-nfv-solv3-subscriptions
Change-Id: I603e32090303af080b17e549a0caf7e862aa7e1e
f24afcf705