docs: add Trivy scan badges

| Input / Variable | Description                              | Default value     |

| --------------------- | ---------------------------------------- | ----------------- |

| `image` / `POSTMAN_IMAGE` | The Docker image used to run Postman CLI. | `registry.hub.docker.com/postman/newman:latest` |

| `image` / `POSTMAN_IMAGE` | The Docker image used to run Postman CLI. | `registry.hub.docker.com/postman/newman:latest` <br/>[![Trivy Badge](https://to-be-continuous.gitlab.io/doc/secu/trivy-badge-POSTMAN_IMAGE.svg)](https://to-be-continuous.gitlab.io/doc/secu/trivy-POSTMAN_IMAGE) |

| `collections` / `POSTMAN_COLLECTIONS` | The matcher to select Postman collection file(s) to run. | `postman/*collection.json` |

| `extra-args` / `POSTMAN_EXTRA_ARGS` | Newman extra [run options](https://github.com/postmanlabs/newman#command-line-options) (to use global variables, an environment or a data source for e.g.) | _none_ |

| `review-enabled` / `REVIEW_ENABLED` | Set to `true` to enable Postman tests on review environments (dynamic environments instantiated on development branches) | _none_ (disabled) |