Update mcrj7.csl

Cases, laws and secondary sources seem now to be cited in accordance with the French McGill Guide. All usual type of source used by legal scholar affected to a style (w/ regards to French McGill Guide).

At line 9, add a link to a doc explaining witch field to use to format in specific way some items (like case, or continental law review).
Merge pull request #524 from f-mb/patch-1

Update mcrj7.csl