message: doc: Fix typo in comment ("ocassionally")
  PR
diff: @@ -9,7 +9,7 @@ use std::u8;
  // The primary invariant that interval sets guards is canonical ordering. That
  // is, every interval set contains an ordered sequence of intervals where
  // no two intervals are overlapping or adjacent. While this invariant is
  -// ocassionally broken within the implementation, it should be impossible for
  +// occasionally broken within the implementation, it should be impossible for
  // callers to observe it.
  //
  // Since case folding (as implemented below) breaks that invariant, we roll
  