Fix legend

Author: award999

Contributor Documentation/README.md

@@ -2,5 +2,6 @@
 
 The following documentation is primarily intended for developers of Swift Extension for VS Code:
 - [Development Setup](./development-setup.md)
+- [Extension Versioning](./extension-versioning.md)
 - [Test Strategy](./test-strategy.md)
-- [Writing Tests](./writing-tests-for-vscode-swift.md.md)
+- [Writing Tests](./writing-tests-for-vscode-swift.md)