Rebuild the docs around tested examples; shrink README.v2.md to a pitch (#2978)

docs_src/completions/tutorial001.py

@@ -0,0 +1,15 @@
+from mcp.server import MCPServer
+
+mcp = MCPServer("GitHub Explorer")
+
+
+@mcp.resource("github://repos/{owner}/{repo}")
+def github_repo(owner: str, repo: str) -> str:
+    """A GitHub repository."""
+    return f"Repository: {owner}/{repo}"
+
+
+@mcp.prompt()
+def review_code(language: str, code: str) -> str:
+    """Review a snippet of code."""
+    return f"Review this {language} code:\n{code}"