Add initial draft of tag pruning config guide

ee/dtr/admin/configure/tag-pruning.md

@@ -0,0 +1,22 @@
+---
+title: Tag Pruning
+description: Skip the management headache of deciding which tags to delete or preserve by configuring a tag pruning policy or enforcing a tag limit in the
+  Docker Trusted Registry
+keywords: registry, online tag pruning, gc, space, disk space
+---
+
+> BETA DISCLAIMER
+>
+> This is beta content. It is not yet complete and should be considered a work in progress. This content is subject to change without notice.
+
+
+You can configure Docker Trusted Registry to automatically clean up images which are abandoned and no longer necessary. You can specify a tag pruning policy on each repository that you manage, and additionally enforce a tag limit.   
+
+## How DTR prunes tags
+
+## Under the hood
+
+
+## Where to go next
+
+- [Online garbage collection](garbage-collection/index.md)