docs: fix inconsistency

Author: il-dat

dbterd/adapters/algos/test_relationship.py

@@ -343,7 +343,7 @@ def get_relationship_type(self, meta: str) -> str:
         Returns:
             str: |
                 Short relationship type. Accepted values: '0n','01','11','nn','n1' and '1n'.
-                And `1n` is default/fallback value
+                And `n1` is default/fallback value
 
         """
         if meta.lower() == "zero-to-many":

docs/nav/metadata/label_override.md

@@ -20,6 +20,9 @@ This will display the model as `customers` in the ERD instead of the actual mode
 
 ### Override Relationship Display Names
 
+!!! note
+    Relationship labels are only rendered in the **Mermaid** target. Other output formats ignore this field.
+
 #### test_relationship algorithm
 
 Add `relationship_label` to your test's meta to customize the relationship name:

docs/nav/metadata/relationship_type.md

@@ -25,6 +25,7 @@ List of accepted values:
 |--------|--------|
 | one-to-many | 1n |
 | zero-to-many | 0n |
+| zero-to-one | 01 |
 | many-to-many | nn |
 | one-to-one | 11 |
 | many-to-one | n1 |