Fix two documentation errors: change `Foo.bar.printFromStatic()` to `Foo.printFromStatic()` in classes.markdown, and replace `map` with `each` in concurrency.markdown to match the actual Wren API.
Fix two documentation errors: change `Foo.bar.printFromStatic()` to `Foo.printFromStatic()` in classes.markdown, and replace `map` with `each` in concurrency.markdown to match the actual Wren API.