Update README based on go template from gluon

Utilize the norwoodj/helm-docs image from docker (more info) and the go template in gluon/docs to generate a new README for the istio-controlplane package. Follow instructions in the Gluon Document https://repo1.dso.mil/platform-one/big-bang/apps/library-charts/gluon/-/blob/master/docs/bb-package-readme.md .

AC:

• README Renders correctly
• Links are correct
• Information is correct