Issue #2020221 by StephaneQ: Update image module description (in yml) mention...

Issue #2020221 by StephaneQ: Update image module description (in yml) mention that an image field is provided.

core/modules/image/image.info.yml

 name: Image
 type: module
-description: 'Provides image manipulation tools.'
+description: 'Defines an image field type and provides image manipulation tools.'
 package: Core
 version: VERSION
 core: 8.x