Add some basic usage to generated README

Closes #2

Author: dbanty

openapi_python_client/__init__.py

@@ -70,7 +70,11 @@ def _build_metadata(self) -> None:
         # README.md
         readme = self.project_dir / "README.md"
         readme_template = self.env.get_template("README.md")
-        readme.write_text(readme_template.render(description=package_description))
+        readme.write_text(
+            readme_template.render(
+                project_name=self.project_name, description=package_description, package_name=self.package_name
+            )
+        )
 
     def _build_models(self) -> None:
         # Generate models

openapi_python_client/templates/README.md

@@ -1 +1,34 @@
+# {{ project_name }}
 {{ description }}
+
+## Usage
+First, create a client:
+
+```python
+from {{ package_name }} import Client
+
+client = Client(base_url="https://api.example.com")
+```
+
+If the endpoints you're going to hit require authentication, use `AuthenticatedClient` instead:
+
+```python
+from {{ package_name }} import AuthenticatedClient
+
+client = AuthenticatedClient(base_url="https://api.example.com", token="SuperSecretToken")
+```
+
+Now call your endpoint and use your models:
+
+```python
+from {{ package_name }}.models import MyDataModel
+from {{ package_name }}.api.my_tag import get_my_data_model
+
+my_data: MyDataModel = get_my_data_model(client=client)
+```
+
+Things to know:
+1. Every path/method combo becomes a Python function with type annotations. 
+1. All path/query params, and bodies become method arguments.
+1. If your endpoint had any tags on it, the first tag will be used as a module name for the function (my_tag above)
+1. Any endpoint which did not have a tag will be in `{{ package_name }}.api.default`

openapi_python_client/templates/client.pyi

@@ -6,6 +6,7 @@ class Client:
     """ A class for keeping track of data related to the API """
 
     base_url: str
+
     def get_headers(self) -> Dict[str, str]:
         """ Get headers to be used in all endpoints """
         return {}
@@ -15,6 +16,7 @@ class AuthenticatedClient(Client):
     """ A Client which has been authenticated for use on secured endpoints """
 
     token: str
+
     def get_headers(self) -> Dict[str, str]:
         """ Get headers to be used in authenticated endpoints """
         return {"Authorization": f"Bearer {self.token}"}

tests/test___init__.py

@@ -135,7 +135,9 @@ def test__build_metadata(self, mocker):
             project_name=project.project_name, package_name=project.package_name, description=description
         )
         pyproject_path.write_text.assert_called_once_with(pyproject_template.render())
-        readme_template.render.assert_called_once_with(description=description)
+        readme_template.render.assert_called_once_with(
+            description=description, project_name=project.project_name, package_name=project.package_name,
+        )
         readme_path.write_text.assert_called_once_with(readme_template.render())
 
     def test__build_models(self, mocker):