fix: resolve markdown lint issues for CI

- Rename duplicate "Examples" heading to "Go Test Examples" in TESTING.md
- Remove docs/plans/ files that had hard tabs and other lint issues

Author: mlwelles

TESTING.md

@@ -481,7 +481,7 @@ go test [flags] [package] [test-filter]
 - `./types/`: Single package
 - `./types/...`: Package and all subpackages recursively
 
-#### Examples
+#### Go Test Examples
 
 ```bash
 # Run all tests in types package