add discovery segment

docs/documentation.md

@@ -96,6 +96,21 @@ def condition_function(args: ConditionArgs) -> bool:
     ...
 ```
 
+## Discovery of `Runners` and `Tests`
+
+- Runners will be discovered, if they are defined in a moduled of name `runner_*.py` including a class of name `Runner*`.
+
+- Tests will be discovered by filename as long as they are placed in the parent dir of `runner_*.py` or in any subdirectory.
+
+```
+DIR parent_dir
+├── FILE runner_*.py
+├── FILE test1.py
+└── DIR subdir
+    ├── DIR subsubdir
+    │   └── test2.py
+    └── test3.py
+```
 
 # Create custom Tests