message: Document the `update` task.
diff: @@ -84,6 +84,7 @@ roboter provides a variety of tasks. To run them, run roboter and provide the ta
  | [`qa`](#the-qa-task) | Runs code analysis, tests and checks dependencies. |
  | [`release`](#the-release-task) | Releases a new version. |
  | [`test`](#the-test-task) | Runs tests. |
  +| [`update`](#the-update-task) | Updates the Node.js version. |
  If you don't specify a task, the `qa` task is run as default task.
  @@ -382,6 +383,26 @@ To adjust test execution, you can provide a [`mocha.opts`](https://mochajs.org/#
  - `--exit`
  - `--ui tdd`
  +### The `update` task
  +
  +This task updates the Node.js version to the latest available LTS version as long as it is newer than the currently used version, commits it and optionally pushes the changes.
  +
  +I.e. if you're on version `8.2.0`, it will update to the latest LTS (at the time of writing `10.16.3`). But if you're on `12.11.0` (the most current version at the time of writing), it won't change anything.
  +
  +### Flags
  +
  +| Flag | Alias | Description |
  +|-|-|-|
  +| --no-push | -p | Prevents pushing the changes. |
  +| --node | -n | Whether Node.js should be updated. True by default, currently has no effect. |
  +
  +### Exit codes
  +
  +| Exit code | Description |
  +|-|-|
  +| 0 | Success (either updates were made or were not necessary) |
  +| 1 | Update failed |
  +
  ## Running the tests
  To run the tests run the following command:
  