Docstring parsing using docstring-parser (#76)

* adds description for params

* add test for missing param description

* adds docstring parsing to OpenAISchema

* docs

---------

Co-authored-by: Jason Liu <jxnl@users.noreply.github.com>

docs/index.md

@@ -130,20 +130,29 @@ from instructor import OpenAISchema
 from pydantic import Field
 
 class UserDetails(OpenAISchema):
-    "Correctly extracted user information"
+    """"
+    Correctly extracted user information
+    :param age: age of the user
+    """
     name: str = Field(..., description="User's full name")
     age: int
 ```
 
-In this updated schema, we use the `Field` class from `pydantic` to add descriptions to the `name` field. The description provides information about the field, giving even more context to the language model.
-
+In this updated schema, we use the `Field` class from `pydantic` to add descriptions to the `name` field. Moreover, we use the docstring to add information for the parameter `age`. 
+In both cases, the description provides information about the fields, giving even more context to the language model.
+Information from the docstring is extracted using [docstring-parser](https://github.com/rr-/docstring_parser) which supports different docstring styles.
+Note that if the `Field` contains a description for a parameter as well as the docstring, the `Field`'s description is used. 
 
 !!! note "Code, schema, and prompt"
-     We can run `openai_schema` to see exactly what the API will see, notice how the docstrings, attributes, types, and field descriptions are now part of the schema. This describes on this library's core philosophies.
+We can run `openai_schema` to see exactly what the API will see, notice how the docstrings, attributes, types, and parameter descriptions are now part of the schema. This describes on this library's core philosophies.
 
     ```python hl_lines="2 3"
     class UserDetails(OpenAISchema):
-        "Correctly extracted user information"
+        """
+        Correctly extracted user information
+        :param name: the user's full name
+        :param age: age of the user
+        """
         name: str = Field(..., description="User's full name")
         age: int
 
@@ -158,11 +167,12 @@ In this updated schema, we use the `Field` class from `pydantic` to add descript
         "type": "object",
         "properties": {
         "name": {
-            "description": "User's full name",
-            "type": "string"
+            "type": "string",
+            "description": "User's full name"
         },
         "age": {
             "type": "integer"
+            "description": "age of the user"
         }
         },
         "required": [
@@ -182,7 +192,11 @@ from instructor import OpenAISchema
 from pydantic import Field
 
 class UserDetails(OpenAISchema):
-    "Correctly extracted user information"
+    """
+    Correctly extracted user information
+    :param name: the user's full name
+    :param age: age of the user
+    """
     name: str = Field(..., description="User's full name")
     age: int