Added regression tests for navigation

_config.yml

docs/tests/42.md

docs/tests/index.md

docs/tests/navigation/exclude/excluded-child.md

docs/tests/navigation/exclude/excluded-grandchild.md

docs/tests/navigation/exclude/excluded.md

...ests/navigation/exclude/non-excluded-child-of-excluded.md

docs/tests/navigation/exclude/non-excluded-child.md

...navigation/exclude/non-excluded-grandchild-of-excluded.md

docs/tests/navigation/exclude/non-excluded-grandchild.md

docs/tests/navigation/exclude/non-excluded.md

docs/tests/navigation/exclude/untitled.md

docs/tests/navigation/grandparent/a.md

docs/tests/navigation/grandparent/b.md

docs/tests/navigation/grandparent/ca.md

docs/tests/navigation/grandparent/cb.md

docs/tests/navigation/grandparent/dca.md

docs/tests/navigation/grandparent/dcb.md

docs/tests/navigation/index.md

docs/tests/navigation/order/default/10.md