Keys of seed part of config is not explained in the documentation

**Actual Behaviour**

The documentation does not mention what the keys to the 'seed' property are. The example shows 'domain' and 'test'.

**Expected Behaviour**

The documentation should explain what the keys are. What do *domain* and *test* mean?

**Steps to reproduce it**

Read the docs

**Would you like to work on the issue?**

I would do a PR if I understood the correct behaviour.

Start by finding the documentation section containing the seed example, then trace the seed configuration in the plugin to confirm what the domain and test keys mean. Update the documentation to explain those keys and verify that the example matches the documented behavior.

Written by the indexing model from the issue text.