Ensure that checks are run from repo root

tools/check

 #!/usr/bin/env bash
 #  check: Ensure that proper formatting has been used.
 
+# Ensure we run from the lesson directory
+cd "$( dirname "${BASH_SOURCE[0]}" )" && cd ..
+
 # Show all of the FIXMEs in the lessons content
 grep -i -n FIXME ??-*.md