For PR|PER, check that the SOTD contains a link to wbs
use info message instead of warning
PR #42 (For PR|PER, check that the SOTD contains a link to wbs).

Added a couple of test cases for this new rule.
Merge pull request #42 from w3c/denis/pr-per-ac-review

For PR|PER, check that the SOTD contains a link to wbs