Change log for registry guide

Changes between v11.05 and v11.12

The standardID value identifying the capability for VAMDC nodes has changed from ivo://vamdc/std/TAP-XSAMS to ivo://vamdc/std/VAMDC-TAP. The examples of querying have been updated accordingly.

The namespace of the schema ruling the VAMDC-TAP capability has changed from http://www.vamdc.eu/xml/TAPXSAMS/v1.0 to http://www.vamdc.org/xml/VAMDC-TAP/v1.0. The section on registering services have been updated accordingly.

The recommended version of the VAMDC client-library for the registry is changed from 2.0 to 3.0.

The sample project associated with the guide used some out-of-date constants. These have been updated to the current standard.