add link to overrides page from docs project structure page

Author: devalog

fern/products/docs/pages/getting-started/project-structure.mdx

@@ -111,10 +111,14 @@ title: Fern's Documentation
 <AccordionGroup>
   <Accordion title="OpenAPI">
     The `openapi` folder contains the OpenAPI Specification file for your API Reference section. Fern will read either a YAML or JSON file from this folder to generate the API Reference documentation. If you don't have an API Reference section, you can skip this folder.
+
+    In addition to your specification file, you can optionally [add an overrides file](/api-definitions/overview/overrides) for additional customizations. 
+
     <CodeBlock title="fern/openapi">
     ```bash
     openapi
-    └─ openapi.yaml # OR openapi.json
+    ├─ openapi.yaml # OR openapi.json
+    └─ overrides.yaml 
     ```
     </CodeBlock>
 
@@ -123,12 +127,16 @@ title: Fern's Documentation
   </Accordion>
   <Accordion title="Fern Definition">
     The `definition` folder contains the Fern Definition YAML files used to generate the API Reference section. If you don't have an API Reference section, you can skip this folder.
+
+    In addition to your specification file, you can optionally [add an overrides file](/api-definitions/overview/overrides) for additional customizations. 
+
     <CodeBlock title="fern/definition">
     ```bash
     definition
     ├─ pets.yaml
     ├─ owners.yaml
     ├─ stores.yaml
+    ├─ overrides.yaml
     └─ api.yaml
     ```
     </CodeBlock>
@@ -137,14 +145,18 @@ title: Fern's Documentation
 
   </Accordion>
   <Accordion title="Multiple APIs">
-    If you have multiple APIs, you can organize them into separate folders within the `apis` folder. Each API should have its own API definition. For example:
+    If you have multiple APIs, you can organize them into separate folders within the `apis` folder. Each API should have its own API definition and [(optional) overrides file](/api-definitions/overview/overrides). 
+    
+    For example:
     <CodeBlock title="fern/apis">
     ```bash
     apis
     ├─ admin
-    │  └─ openapi.json 
+    │  ├─ openapi.json 
+    │  └─ overrides.yaml
     ├─ user
-    │  └─ openapi.yaml
+    │  ├─ openapi.yaml 
+    │  └─ overrides.yaml
     ```
     </CodeBlock>