Commits on Jul 13, 2017

1. trivial: adjust docs to clearly state that licenses are SPDX expressions …

   Previously the doc was a bit ambiguous about the actual format employed
   for licenses. The format expectation is the actual SPDX license expression
   format as described in the SPDX specification.
   Clearly state this and point to the specification URL for reference on the
   format.
   
   Additionally, while SPDX must be parsed as case-insensitive it's considered
   best practice to use strict-casing in examples, so change to that.
   
   Closes ximion#122

   

   hsitter committed Jul 13, 2017
   945238a