docs: Format Markdown with Prettier.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

docs/documentation/api.md

@@ -134,7 +134,7 @@ For the Python examples, you'll write the example in
 automatically in Zulip's automated test suite. The code there will
 look something like this:
 
-``` python
+```python
 @openapi_test_function('/messages/render:post')
 def render_message(client: Client) -> None:
     # {code_example|start}
@@ -237,10 +237,11 @@ above.
    declared using `REQ`.
 
    You can check your formatting using these helpful tools.
+
    - `tools/check-openapi` will verify the syntax of `zerver/openapi/zulip.yaml`.
    - `tools/test-backend zerver/tests/test_openapi.py`; this test compares
-      your documentation against the code and can find many common
-      mistakes in how arguments are declared.
+     your documentation against the code and can find many common
+     mistakes in how arguments are declared.
    - `test-backend`: The full Zulip backend test suite will fail if
      any actual API responses generated by the tests don't match your
      defined OpenAPI schema. Use `test-backend --rerun` for a fast