Tweak path to mount the microservice at an API end point

Summary:
The goal is to mount the microservice at /docker/registry

As such, the following tweaks are done:

• a favicon doesn't make sense, as it's not intended to be used as a root at Nasqueron and 3rdparty would want a generic Docker favicon or something for their project.
• /docker/registry/registry/stats → /docker/registry/stats

Ref T1461

Test Plan:

• {{URL}}/docker/registry/status
• {{URL}}/docker/registry/stats
• {{URL}}/docker/registry/repository/getAll

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1461

Differential Revision: https://devcentral.nasqueron.org/D1876