Update comment on adaptive step-sizing

I noticed the description of the comment on adaptive step-sizing defined δ_{n, n} as the inverse of what it looks to be in code. If I'm wrong, just close this issue

Author: packquickly

diffrax/step_size_controller/adaptive.py

@@ -423,8 +423,8 @@ def adapt_step_size(
         # h_n is the nth step size
         # ε_n     = atol + norm(y) * rtol with y on the nth step
         # r_n     = norm(y_error) with y_error on the nth step
-        # δ_{n,m} = norm(y_error / (atol + norm(y) * rtol)) with y_error on the nth
-        #                                                   step and y on the mth step
+        # δ_{n,m} = norm(y_error / (atol + norm(y) * rtol))^(-1) with y_error on the nth
+        #                                                        step and y on the mth step
         # β_1     = pcoeff + icoeff + dcoeff
         # β_2     = -(pcoeff + 2 * dcoeff)
         # β_3     = dcoeff