[doc,geometry,multibody] Add refs to Hydroelastic User Guide (#16549)

* [doc,geometry,multibody] Add refs to Hydroelastic User Guide

Closes: #15743

The module ... it is written.

geometry/proximity_properties.h

@@ -54,9 +54,8 @@ extern const char* const kPointStiffness;  ///< Point stiffness property
        - differentiating between a rigid and compliant geometry
        - accounting for differences between tessellated meshes and half spaces.
 
- @todo Add reference to discussion of hydroelastic proximity properties along
- the lines of "For the full discussion of preparing geometry for use in the
- hydroelastic contact model, see `@ref MODULE_NOT_WRITTEN_YET`.
+ For the full discussion of preparing geometry for use in the hydroelastic
+ contact model, see @ref creating_hydro_reps.
  */
 //@{
 
@@ -116,10 +115,9 @@ void AddContactMaterial(
                               parameter that guides the level of mesh
                               refinement. It has length units (in meters) and
                               roughly corresponds to a typical edge length in
-                              the resulting mesh.
-                              See @ref MODULE_NOT_WRITTEN_YET. This will be
-                              ignored for geometry types that don't require
-                              tessellation.
+                              the resulting mesh.  See @ref hug_properties.
+                              This will be ignored for geometry types that don't
+                              require tessellation.
  @param[in,out] properties    The properties will be added to this property set.
  @throws std::exception       If `properties` already has properties with the
                               names that this function would need to add.
@@ -129,26 +127,26 @@ void AddRigidHydroelasticProperties(double resolution_hint,
 
 /** Overload, intended for shapes that don't get tessellated in their
  hydroelastic representation (e.g., HalfSpace and Mesh).
- See @ref MODULE_NOT_WRITTEN_YET.  */
+ See @ref hug_properties.  */
 void AddRigidHydroelasticProperties(ProximityProperties* properties);
 
-// TODO(SeanCurtis-TRI): Add module that explains resolution hint and reference
-//  it in the documentation below.
 /** Adds properties to the given set of proximity properties sufficient to cause
  the associated geometry to generate a compliant hydroelastic representation.
  The geometry's pressure field will be the function p(e) = Ee, where E is the
  hydroelastic modulus stored in the given `properties`.
 
- @param resolution_hint       If the geometry is to be tessellated, it is the
-                              parameter that guides the level of mesh
-                              refinement. It has length units (in meters) and
-                              roughly corresponds to a typical edge length in
-                              the resulting mesh. This will be ignored for
-                              geometry types that don't require tessellation.
- @param hydroelastic_modulus  A multiplier that maps penetration to pressure.
- @param[in,out] properties    The properties will be added to this property set.
- @throws std::exception       If `properties` already has properties with the
-                              names that this function would need to add.
+ @param resolution_hint      If the geometry is to be tessellated, it is the
+                             parameter that guides the level of mesh
+                             refinement. It has length units (in meters) and
+                             roughly corresponds to a typical edge length in
+                             the resulting mesh.  See @ref hug_properties.
+                             This will be ignored for geometry types that don't
+                             require tessellation.
+ @param hydroelastic_modulus A multiplier that maps penetration to pressure. See
+                             @ref hug_properties.
+ @param[in,out] properties   The properties will be added to this property set.
+ @throws std::exception      If `properties` already has properties with the
+                             names that this function would need to add.
  @pre 0 < `resolution_hint` < ∞, 0 < `hydroelastic_modulus`, and `properties`
       is not nullptr. */
 void AddCompliantHydroelasticProperties(double resolution_hint,
@@ -162,7 +160,8 @@ void AddCompliantHydroelasticProperties(double resolution_hint,
  @param slab_thickness       The distance from the half space boundary to its
                              rigid core (this helps define the extent field of
                              the half space).
- @param hydroelastic_modulus A multiplier that maps penetration to pressure.
+ @param hydroelastic_modulus A multiplier that maps penetration to pressure. See
+                             @ref hug_properties.
  @param[out] properties      The properties will be added to this property set.
  @throws std::exception If `properties` already has properties with the names
                         that this function would need to add.

multibody/parsing/parsing_doxygen.h

@@ -279,7 +279,7 @@ drake::geometry::CollisionFilterDeclaration::ExcludeWithin()).
 If present, this element sets the compliance type of the element being defined
 to be compliant, as opposed to rigid, in hydroelastic contact models.
 
-@see @ref tag_drake_proximity_properties, @ref MODULE_NOT_WRITTEN_YET
+@see @ref tag_drake_proximity_properties, @ref creating_hydro_reps
 
 @subsection tag_drake_damping drake:damping
 
@@ -386,7 +386,7 @@ under `(hydroelastic, hydroelastic_modulus)`.
 
 @see drake::geometry::ProximityProperties,
 @ref mbp_hydroelastic_materials_properties "Hydroelastic contact",
-@ref MODULE_NOT_WRITTEN_YET
+@ref hug_properties
 
 @subsection tag_drake_ignored_collision_filter_group drake:ignored_collision_filter_group
 
@@ -468,7 +468,7 @@ exact semantics depend on the geometry being generated. Within some practical
 limits, smaller values will select shorter edge lengths and a finer mesh, larger
 values will select longer edge lengths and a coarser mesh.
 
-@see @ref tag_drake_proximity_properties, @ref MODULE_NOT_WRITTEN_YET
+@see @ref tag_drake_proximity_properties, @ref hug_properties
 
 @subsection tag_drake_mu_dynamic drake:mu_dynamic
 
@@ -572,7 +572,7 @@ drake::geometry::ProximityProperties
 If present, this element sets the compliance type of the element being defined
 to be rigid, as opposed to compliant, in hydroelastic contact models.
 
-@see @ref tag_drake_proximity_properties, @ref MODULE_NOT_WRITTEN_YET
+@see @ref tag_drake_proximity_properties, @ref creating_hydro_reps
 
 @subsection tag_drake_rotor_inertia drake:rotor_inertia