fixed haddock header in Abacus.Intenal module

src/Abacus/Internal.hs

@@ -22,9 +22,9 @@ You should have received a copy of the GNU Affero General Public
 License along with this program.  If not, see
 <https://www.gnu.org/licenses/>.
 
-# Important Note
+IMPORTANT NOTE
 
-This module should only be imported directl by the Abacus module and
+This module should only be imported directly by the Abacus module and
 the testing suite.  Anything contained herein should be considered
 subject to change without notice.