Clarify deprecated language and use explicit link instead of vague "here"

Author: stevepiercy

plone/deprecated.md

@@ -4,7 +4,7 @@
 -	Plone 5.x is no longer supported.
 -	It is strongly recommended to migrate to the latest available Plone version. See https://plone.org/download/release-schedule for details.
 
-The official Docker images for Plone 5.x and Plone 4.x are available here.
+The official Docker images for Plone 4.x and Plone 5.x are available at https://hub.docker.com/_/plone. These images are depecrated.
 
 Beginning with Plone 6.x, the frontend and backend run in separate Docker images. There's also a a ZEO server Docker image. All Plone 6.0 and later images are supported by the Plone Foundation and are maintained by community volunteers.