Apply suggestion from @wyattscarpenter

Author: wyattscarpenter

test-data/unit/README.md

@@ -35,7 +35,7 @@ with text "abc..."
   in this context; also, in all other contexts, such as line-continuation, the backslash is treated
   as it normally would be in a python source file)
 - repeating `# E: ` several times in one line indicates multiple expected errors in one line
-- `W: ...` and `N: ...` works exactly like `E: ...`, but report a warning and a note respectively
+- `W: ...` and `N: ...` work exactly like `E: ...`, but report a warning and a note respectively
 - lines that don't contain the above should cause no type check errors
 - lines that begin with `--` are test-file-format comments, and will not appear in the tested python
   source code