Add Documentation on how-to add custom RoboTasks or DeployTasks

[mwr]

Per project one might have to have to customize exsting tasks or add additional tasks.

There needs to be some documentation on how to create local tasks beneath a src dir.
Furthermore some doc on how to include tasks using composer might be helpful as well.

[phronesis]

Any informal docs to this, I want to import a database from n98-magerun2.phar db:dump to the database before installing magento.

[mwr]

There are no docs available right now on how to do this.
If you want to import that dump on the database that is created on the build-system then you would have to create a RoboTask that gets executed while the magento-setup stage.
A tutorial on how to create tasks for robo can be found here: http://robo.li/getting-started/
If you want to import a dump on the database of your deploy-target then you would need to extend the deployer scripts by adding a command to the pipeline in deploy.php.
Here is a link to the deployer documentation: https://deployer.org/docs/tasks