This fix tries to add the registry mirrors information in the output
of `docker info`.
In our active deployment, we use registry mirrors to help speeding
up the `docker pull`. In the current output of `docker info`,
registry mirrors is not present though it is available in `/info` API.
I think it makes sense to add the registry mirrors to `docker info`,
similiar to insecure registries.
This fix adds the registry mirrors to the output of `docker info`:
```
Registry Mirrors:
https://192.168.1.2/http://registry.mirror.com:5000/
```
An integration test has been added to cover the changes.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
Upstream-commit: 0f6acff796f7b3c9b981dbcae6db6f255ee2055c
Component: engine
384bd6a415