Apply suggestions from code review

Co-authored-by: Rune Søe-Knudsen <41109954+urrsk@users.noreply.github.com>

Author: urfeex

doc/architecture/instruction_executor.rst

@@ -33,7 +33,8 @@ Every motion function comes in two flavours:
   linear tool-space motion towards the pose implied by a joint configuration.
 
 An ``urcl::Pose`` may optionally carry ``q_near`` (``std::optional<urcl::Q>``), a joint configuration
-hint for IK when the pose is sent over the trajectory interface; see :ref:`trajectory_point_interface`.
+hint for inverse kinematic solver to select the desired joint angle solution,
+when the pose is sent over the trajectory interface; see :ref:`trajectory_point_interface`.
 
 The Instruction Executor uses the :ref:`trajectory_point_interface` and the
 :ref:`reverse_interface`

doc/architecture/trajectory_point_interface.rst

@@ -105,7 +105,7 @@ representations in 21 datafields. The data fields have the following meaning:
           - 11: MOVEC_POSE_JOINT – ``movec`` with joint via and pose target
           - 12: OPTIMOVEJ_POSE – ``optimovej`` to a pose target
           - 13: OPTIMOVEL_JOINT – ``optimovel`` to the pose implied by a joint target
-          - 51: SPLINE
+          - 51: SPLINE - Cubic or quintic spline.
    =====  =====
 
 where