Fix some typos

CONTRIBUTING.md

@@ -559,11 +559,11 @@ When declaring fixture functions and requesting them in the same Python module,
 there is a risk of accidentally using the fixture function declared in the 
 global scope instead of requesting it in the test case function parameters.
 
-To prevent this problme, it is recommended to add a "fixture" prefix or suffix 
+To prevent this problem, it is recommended to add a "fixture" prefix or suffix 
 to the fixture function name and use the `name` argument in the `pytest.fixture`
 decorator to name the fixture.
 
-Here's An example of using the `name` argument in `pytest.fixture`:
+Here's an example of using the `name` argument in `pytest.fixture`:
 
 ```python
 import pytest