Update docs, add dev dependencies, and test script

Revise README with improved installation and usage instructions, add development section, and simplify Python usage example. Bump version to 1.1.2, add optional 'dev' dependencies (pylint) in pyproject.toml, and introduce a minimal test.py script for upload testing.

test.py

@@ -0,0 +1,7 @@
+from gofilepy import GofileClient
+
+client = GofileClient()
+# client = GofileClient(token="YOUR_TOKEN_HERE")  # Optional token for private uploads
+file = client.upload(file=open("./test.py", "rb"))
+print(file.name)
+print(file.page_link)  # View and download file at this link