Improve error message when user selects tailoring instead of benchmark
Improve error message when user selects tailoring instead of benchmark

Previously:
OpenSCAP Error: Find element 'Tailoring' while expecting element: 'Benchmark' [benchmark.c:140]
Failed to import XCCDF content from 'xccdf.xml'. [benchmark.c:73]

Now:
OpenSCAP Error: The selected checklist document is not 'XCCDF Checklist', but 'XCCDF Tailoring'. [xccdf_session.c:485]

ybznek/openscap,redhatrises/openscap,OpenSCAP/openscap,Hexadorsimal/openscap,openprivacy/openscap,Hexadorsimal/openscap,OpenSCAP/openscap,OpenSCAP/openscap,openprivacy/openscap,Hexadorsimal/openscap,jan-cerny/openscap,jan-cerny/openscap,redhatrises/openscap,jan-cerny/openscap,mpreisler/openscap,ybznek/openscap,Hexadorsimal/openscap,jan-cerny/openscap,mpreisler/openscap,openprivacy/openscap,OpenSCAP/openscap,ybznek/openscap,redhatrises/openscap,ybznek/openscap,redhatrises/openscap,mpreisler/openscap,jan-cerny/openscap,openprivacy/openscap,redhatrises/openscap,redhatrises/openscap,OpenSCAP/openscap,ybznek/openscap,Hexadorsimal/openscap,ybznek/openscap,openprivacy/openscap,mpreisler/openscap,openprivacy/openscap,Hexadorsimal/openscap,OpenSCAP/openscap,mpreisler/openscap,jan-cerny/openscap,mpreisler/openscap