Promote the v2 README to README.md ahead of the first v2 beta (#3014)

pyproject.toml

@@ -2,7 +2,7 @@
 name = "mcp"
 dynamic = ["version", "dependencies"]
 description = "Model Context Protocol SDK"
-readme = "README.v2.md"
+readme = "README.md"
 requires-python = ">=3.10"
 authors = [{ name = "Model Context Protocol a Series of LF Projects, LLC." }]
 maintainers = [
@@ -175,7 +175,6 @@ executionEnvironments = [
 [tool.ruff]
 line-length = 120
 target-version = "py310"
-extend-exclude = ["README.md", "README.v2.md"]
 
 [tool.ruff.lint]
 select = [