Clarify when the last u is ignored

Author: SouthEndMusic

docs/src/methods.md

@@ -93,7 +93,7 @@ A = SmoothedConstantInterpolation(u, t; d_max = 10)
 plot!(A)
 ```
 
-Note that `u[end]` is ignored.
+Note that `u[end]` is ignored, except when using extrapolation types `Constant` or `Extension`.
 
 ## Quadratic Spline
 

src/interpolation_caches.jl

@@ -372,8 +372,8 @@ end
 
 It is a method for interpolating constantly with forward fill, with smoothing around the
 value transitions to make the curve continuously differentiable while the integral never
-drifts far from the integral of constant interpolation. `u[end]` is ignored for extrapolation types
-`None` (default) and `Periodic`.
+drifts far from the integral of constant interpolation. `u[end]` is ignored,
+except when using extrapolation types `Constant` or `Extension`.
 
 ## Arguments