Adding documentation about Use local GitLab container registry with AutoDevops pipelines

What does this Merge Request do?

Adding documentation about Using local GitLab container registry with AutoDevops pipelines Also added information about how to use the local insecure registry or registry with self-signed certificate with minikube as a kubernetes runner

I've tried locally to test AutoDevops pipelines and with local registry I faced with next errors:

• if local registry created with self-signed certificate:

$ /build/build.sh
Logging to GitLab Container Registry with CI credentials...
Error response from daemon: Get https://gdk.test:5000/v2/: x509: certificate signed by unknown authority
ERROR: Job failed: command terminated with exit code 1

• if local registry created with http protocol:

$ /build/build.sh
Logging to GitLab Container Registry with CI credentials...
Error response from daemon: Get https://gdk.test:5000/v2/: http: server gave HTTP response to HTTPS client
ERROR: Job failed: command terminated with exit code 1

Merge Request checklist

• Documentation added/updated, if needed.