Fix typo in docs

Author: gray-adeyi

docs/index.md

@@ -40,7 +40,7 @@ $ uv add pypaystack2
 # For webhook cli
 $ pip install -U "pypaystack2[webhook]"
 or install with uv
-$ uv add "pypaystack2[webhook"
+$ uv add "pypaystack2[webhook]"
 ```
 
 ## Examples