How to add optional file paths to monitor under the `packages` field in `release-please-config.json`

How do i add additional paths to trigger a release in a `monorepo`.
I have inherited a repo and the structure is not like any of the examples and its not feasible to restructure it just for `release-please`

For example updating a file under `/src/app` works as expected . A release is generated
```json
"packages": { "/src/app1": { /* files that are modified under this path trigger a release */} }
```

However I need to find a way to add optional file paths to monitor?

eg...
```json
{
"include-component-in-tag": true,
"include-v-in-tag": false,
"tag-separator": "@",
"separate-pull-requests": true,
"packages": {
"/src/app1": {
"release-type": "simple",
"package-name": "app1", << seems to have no effect
"include-paths": [ <<<<<<<<<<< made up key
"/src/app1",
".docker/app1-dockerfile"
]
}
},
"$schema": "https://raw.githubusercontent.com/googleapis/release-please/main/schemas/config.json"
}
```