docs: further tweaks following review

Author: stevenhsd

docs/user_guidance/entity_relationships.md

@@ -11,14 +11,14 @@ tags:
 
 Sometimes a user may choose to use the file transformation stage to `normalise` a heavily nested dataset into separate entities during the initial reading of data. This would be done by specifying different entities in the dataset section of the contract configuration in the `dischema` file. This allows for easier interaction when customising errors in the data contract or writing transformations in the business rules.
 
-`Normalising` assets can lead to more complex validations being required. For example in the dataset:
+`Normalising` assets can lead to more complex validations being required. For example in the flights dataset:
 
 ```mermaid
 erDiagram
-    COUNTRY ||--o{ AIRPORT : ""
+    COUNTRY ||--|{ AIRPORT : ""
     AIRPORT ||--o{ FLIGHT : ""
     FLIGHT ||--o{ PASSENGER : ""
-    AIRPORT ||--o{ STAFF_MEMBER : ""
+    AIRPORT ||--|{ STAFF_MEMBER : ""
 ```
 
 ### Missing Parent Records

zensical.toml

@@ -57,6 +57,9 @@ nav = [
                 {"Refdata" = [
                     {"Refdata Types" = "advanced_guidance/package_documentation/refence_data_types.md"},
                     {"Refdata Loaders" = "advanced_guidance/package_documentation/refdata_loaders.md"},
+                ]},
+                {"Entity Relationships" = [
+                    {"Entity Hierarchy" = "advanced_guidance/package_documentation/entity_hierarchy.md"}
                 ]}
             ]},
             {"Feedback" = [