Create README for PyPi (#154)

# PR Description
The `arcade/pyproject.toml` wasn't able to find the `README.md` file
because it must be a subpath of `arcade-ai/arcade`. I created a simple
README for PyPi

arcade/README.md

@@ -0,0 +1,13 @@
+# Arcade AI Python SDK and CLI
+
+[Arcade AI](https://arcade-ai.com?ref=pypi) provides developer-focused tooling and APIs designed to improve the capabilities of LLM applications and agents.
+
+By removing the complexity of connecting agentic applications with your users' data and services, Arcade AI enables developers to focus on building their agentic applications.
+
+To learn more, check out our
+- [Website](https://arcade-ai.com?ref=pypi)
+- [GitHub](https://github.com/ArcadeAI/arcade-ai)
+- [Documentation](https://docs.arcade-ai.com)
+- [Discord](https://discord.com/invite/GUZEMpEZ9p)
+- [X](https://x.com/TryArcade)
+- [LinkedIn](https://www.linkedin.com/company/arcade-ai)

arcade/pyproject.toml

@@ -2,7 +2,7 @@
 name = "arcade-ai"
 version = "0.1.1"
 description = "Arcade AI Python SDK and CLI"
-readme = "../README.md"
+readme = "README.md"
 packages = [
     {include="arcade", from="."}
 ]