[fvproblem][doc] Improve docstring of enableInternalDirichletConstraints()

dumux/common/fvproblem.hh

@@ -249,10 +249,18 @@ public:
     /*!
      * \brief If internal Dirichlet contraints are enabled
      * Enables / disables internal (non-boundary) Dirichlet constraints. If this is overloaded
-     * to return true, the assembler calls problem.hasInternalDirichletConstraint(element, scv)
-     * which has to return a bool signifying whether the dof associated with is contraint.
-     * If true is returned for a dof, the assembler calls problem.internalDiririchlet(element, scv)
-     * which has to return the enforced Dirichlet values for that dof.
+     * to return true, the assembler calls problem.hasInternalDirichletConstraint(element, scv).
+     * This means you have to implement the following member function
+     *
+     *    bool hasInternalDirichletConstraint(const Element& element, const SubControlVolume& scv) const;
+     *
+     * which returns a bool signifying whether the dof associated with the element/scv pair is contraint.
+     * If true is returned for a dof, the assembler calls problem.internalDiririchlet(element, scv).
+     * This means you have to additionally implement the following member function
+     *
+     *    PrimaryVariables internalDiririchlet(const Element& element, const SubControlVolume& scv) const;
+     *
+     * which returns the enforced Dirichlet values the dof associated with the element/scv pair.
      */
     static constexpr bool enableInternalDirichletConstraints()
     { return false; }