docs: add Trivy scan badges

| Input / Variable | Description                                                                                                            | Default value                                 |

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

| `image` / `BRU_IMAGE` | The Docker image used to run the [Bruno CLI](https://docs.usebruno.com/bru-cli/overview).                             | `registry.hub.docker.com/library/node:lts-alpine` |

| `image` / `BRU_IMAGE` | The Docker image used to run the [Bruno CLI](https://docs.usebruno.com/bru-cli/overview).                             | `registry.hub.docker.com/library/node:lts-alpine` <br/>[![Trivy Badge](https://to-be-continuous.gitlab.io/doc/secu/trivy-badge-BRU_IMAGE.svg)](https://to-be-continuous.gitlab.io/doc/secu/trivy-BRU_IMAGE) |

| `collections` / `BRU_COLLECTIONS` | The matcher to select Bruno collection directory(ies) to run.                                                          | `bruno`                                       |

| `base-url` / `BRU_BASE_URL` | Explicit base url environment to test.<br/>_Auto-evaluated by default ([see below chapter](#base-url-auto-evaluation))._ | _none_ (auto-evaluated)                             |

| `extra-args` / `BRU_EXTRA_ARGS` | Bruno extra [run options](https://docs.usebruno.com/bru-cli/overview#options)                                         | _none_                                        |