Fix Teardown intent filtering

In my [refactoring of intent filtering](de5dff3d4a5ef58d0c7cde5e9695dfacdc5ecd40), I introduced a bug that causes teardown URLs (e.g. `/Teardown/Macintosh+128K+Teardown/21422`) to not open guides correctly. We just need to check for `teardown` as well as `guide` to match a guide view URL.