Add IP address(host) to secret for Instance.redis

[turkenf]

Description of your changes

This PR adds IP address to secret for Instance.redis resource.

Fixes: #387

I have:

• Run make reviewable test to ensure this PR is ready for review.

How has this code been tested

Tested manually:

> k describe secret example-redis-instance-secret -n upbound-system
Name:         example-redis-instance-secret
Namespace:    upbound-system
Labels:       <none>
Annotations:  <none>

Type:  connection.crossplane.io/v1alpha1

Data
====
host:                   13 bytes
attribute.auth_string:  36 bytes

[turkenf]

/test-examples="examples/redis/instance.yaml"

[ulucinar]

Thanks @turkenf, lgtm.