guix: licenses: Add Academic Free License 2.1.

* guix/licenses.scm (afl2.1): New variable.

guix/licenses.scm

@@ -39,6 +39,7 @@
 (define-module (guix licenses)
   #:use-module (srfi srfi-9)
   #:export (license? license-name license-uri license-comment
+            afl2.1
             agpl1 agpl3 agpl3+
             apsl2
             asl1.1 asl2.0
@@ -171,6 +172,11 @@ cases, reduces to #t at macro-expansion time."
 
 (begin-license-definitions license?
 
+(define afl2.1
+  (license "AFL 2.1"
+           "https://spdx.org/licenses/AFL-2.1.html"
+           "https://www.gnu.org/licenses/license-list#AcademicFreeLicense"))
+
 (define agpl1
   (license "AGPL 1"
            "https://gnu.org/licenses/agpl.html"