Correct function names in devdocs (#1036)

Update devdocs to consider #997, and adds the hessian functions from #938

docs/src/devdocs/interpolations.md

@@ -11,21 +11,23 @@ parametrized by the reference element and its characteristic order.
 Ferrite.getrefdim(::Interpolation)
 Ferrite.getrefshape(::Interpolation)
 Ferrite.getorder(::Interpolation)
-Ferrite.shape_gradient(::Interpolation, ::Vec, ::Int)
-Ferrite.shape_gradient_and_value
+Ferrite.reference_shape_gradient(::Interpolation, ::Vec, ::Int)
+Ferrite.reference_shape_gradient_and_value(::Interpolation, ::Vec, ::Int)
+Ferrite.reference_shape_hessian_gradient_and_value(::Interpolation, ::Vec, ::Int)
 Ferrite.boundarydof_indices
 Ferrite.dirichlet_boundarydof_indices
 Ferrite.reference_shape_values!
-Ferrite.shape_gradients!
-Ferrite.shape_gradients_and_values!
+Ferrite.reference_shape_gradients!
+Ferrite.reference_shape_gradients_and_values!
+Ferrite.reference_shape_hessians_gradients_and_values!
 ```
 
 ### Required methods to implement for all subtypes of `Interpolation` to define a new finite element
 
 Depending on the dimension of the reference element the following functions have to be implemented
 
 ```@docs
-Ferrite.shape_value(::Interpolation, ::Vec, ::Int)
+Ferrite.reference_shape_value(::Interpolation, ::Vec, ::Int)
 Ferrite.vertexdof_indices(::Interpolation)
 Ferrite.dirichlet_vertexdof_indices(::Interpolation)
 Ferrite.facedof_indices(::Interpolation)