doc: fix use of old and confusing terminology

Signed-off-by: Rob Donnelly <[email protected]>

Author: rfdonnelly

doc/overview.rst

@@ -302,7 +302,7 @@ changed until it is `released` again.
 Exporter
 ~~~~~~~~
 An exporter registers all its configured resources when it connects to the
-router and updates the resource parameters when they change (such as
+`Coordinator` and updates the resource parameters when they change (such as
 (dis-)connection of USB devices).
 Internally, the exporter uses the normal :any:`Resource` (and
 :any:`ManagedResource`) classes as the rest of labgrid.