package/joe: license is GPL-2.0+

Joe changed the COPYING file from GPL-1.0 to GPL-2.0 in the development
leading up to 3.8:

https://sourceforge.net/p/joe-editor/mercurial/ci/d731f9b3794bc4c896f2efa1c97ac2c82c3365ac/

So change the license to GPL-2.0+

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/joe/joe.mk

@@ -6,7 +6,7 @@
 
 JOE_VERSION = 4.6
 JOE_SITE = http://downloads.sourceforge.net/project/joe-editor/JOE%20sources/joe-$(JOE_VERSION)
-JOE_LICENSE = GPL-1.0+
+JOE_LICENSE = GPL-2.0+
 JOE_LICENSE_FILES = COPYING
 
 ifeq ($(BR2_PACKAGE_NCURSES),y)