Docs: Corrects forward hardware interfaces & Contributing.md (backport #1569) (#1570)

* Docs: Corrects forward controller docs

- Fixes velocity & position controller docs
- Adds "forward_effort_controller"

* Docs: The main branch is "main" now

Author: mergify[bot]

CONTRIBUTING.md

@@ -24,7 +24,7 @@ Please try to include as much information as you can. Details like these are inc
 Contributions via pull requests are much appreciated.
 Before sending us a pull request, please ensure that:
 
-1. You are working against the latest source on the *master* branch.
+1. You are working against the latest source on the *main* branch.
 2. You check existing open, and recently merged, pull requests to make sure someone else hasn't addressed the problem already.
 3. You open an issue to discuss any significant work - we would hate for your time to be wasted.
 

ur_robot_driver/doc/usage/controllers.rst

@@ -97,23 +97,25 @@ Type: :ref:`ur_controllers/GPIOController <io_and_status_controller>`
 
 Allows setting I/O ports, controlling some UR-specific functionality and publishes status information about the robot.
 
+forward_effort_controller
+^^^^^^^^^^^^^^^^^^^^^^^^^
+Type: `effort_controllers/JointGroupEffortController <https://control.ros.org/rolling/doc/ros2_controllers/effort_controllers/doc/userdoc.html#effort-controllers-jointgroupeffortcontroller>`_
+
+Allows setting target joint efforts (torques) directly. The user is therefore responsible for sending commands that are achievable. This controller is useful when implementing compliance or force control strategies.
+
 forward_velocity_controller
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 Type: `velocity_controllers/JointGroupVelocityController <https://control.ros.org/rolling/doc/ros2_controllers/velocity_controllers/doc/userdoc.html#velocity-controllers-jointgroupvelocitycontroller>`_
 
-Allows setting target joint positions directly. The robot tries to reach the target position as
-fast as possible. The user is therefore responsible for sending commands that are achievable. This
-controller is particularly useful when doing servoing such as ``moveit_servo``.
+Allows setting target joint velocities directly. The user is therefore responsible for sending commands that are achievable. This controller is particularly useful when doing servoing such as ``moveit_servo``.
 
 forward_position_controller
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 Type: `position_controllers/JointGroupPositionController <https://control.ros.org/rolling/doc/ros2_controllers/position_controllers/doc/userdoc.html#position-controllers-jointgrouppositioncontroller>`_
 
-Allows setting target joint velocities directly. The user is responsible for sending commands that
-are achievable. This controller is particularly useful when doing servoing such as
-``moveit_servo``.
+Allows setting target joint positions directly. The robot tries to reach the target position as fast as possible. The user is responsible for sending commands that are achievable. This controller is particularly useful when doing servoing such as ``moveit_servo``.
 
 force_mode_controller
 ^^^^^^^^^^^^^^^^^^^^^