Improved documentation about admin api (geopython#1846)

* - added note about admin api routes

* - fixed openapi path

* - open api -> OpenAPI, admin api -> admin API

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Co-authored-by: doublebyte1 <[email protected]>

Author: doublebyte1

docs/source/_static/openapi_admin.png

@@ -14,6 +14,15 @@ The API is enabled with the following server configuration:
     server:
         admin: true # boolean on whether to enable Admin API.
 
+.. note::
+
+    If you generate the OpenAPI definition after enabling the admin API, the admin routes will be exposed on ``/openapi`` 
+
+    .. image:: /_static/openapi_admin.png
+        :alt: admin routes
+        :align: center
+
+    
 Access control
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