Add user documentation for replication

[VrindaMarwah]

Problem Statement:

Provide native support to copy or sync all artifacts from one Pulp container repository/instance to another Pulp container repository/instance.
Currently, migrating artifacts between two Pulp container registries requires manual workflows such as:
Re-pulling images from source and pushing to destination
Re-syncing from upstream registries/repositories

There is no built-in Pulp mechanism to directly clone or mirror artifacts between two Pulp container repositories or instances.

Expectation:

Add a capability to:

1. Copy / mirror all artifacts (blobs + manifests + tags) from one Pulp container to another latest Pulp container
2. Preserves:
   Tags
   Digests
   Artifact checksums
   Versions

I can see there is a page for Pulp Replication but couldn't find steps on how to deploy: https://pulpproject.org/pulpcore/docs/dev/learn/subclassing/replication/?h=repli

[gerrod3]

Seeing as this is your same question on discourse (https://discourse.pulpproject.org/t/support-bulk-artifact-copy-between-pulp-containers/2190), I am going to convert this to a docs issue to add user documentation about replication in Pulp.