Merge branch 'clarify-which-bsd' into 'master'

LICENSE-CODE: Clarify which BSD license is being used

See merge request !472

LICENSE-CODE

 All files in this development, excluding those in docs/ and tex/, are
-distributed under the terms of the BSD license, included below.
+distributed under the terms of the 3-clause BSD license
+(https://opensource.org/licenses/BSD-3-Clause), included below.
 
 Copyright: Iris developers and contributors