https://github.com/doctrine/DoctrineMongoDBBundle/issues/600

Document the following:

• Installation with the package doctrine/data-fixtures
• Creating a fixture class
• Running the command doctrine:mongodb:fixtures:load
• Various options of the command (--purge-with-delete when using encryption to not generate new DEK)
• Link to advanced features: https://www.doctrine-project.org/projects/doctrine-data-fixtures/en/current/how-to/sharing-objects-between-fixtures.html