adding additional hints for contributions (#24)

Author: mhubii

doc/source/contributing.rst

@@ -0,0 +1,9 @@
+Contributing
+============
+If you wish to contribute to any of the projects, please refer to the guidelines for the respective repositories:
+
+- `lbr_fri_ros2_stack <https://github.com/lbr-stack/lbr_fri_ros2_stack/blob/humble/.github/CONTRIBUTING.md>`_:octicon:`link-external`
+- `lbr_fri_idl <https://github.com/lbr-stack/lbr_fri_idl/blob/fri-1/.github/CONTRIBUTING.md>`_:octicon:`link-external`
+- `fri <https://github.com/lbr-stack/fri#contributing>`_:octicon:`link-external`
+- `pyFRI <https://github.com/lbr-stack/pyFRI/blob/main/.github/CONTRIBUTING.md>`_:octicon:`link-external`
+- `lbr_stack_doc <https://github.com/lbr-stack/lbr_stack_doc/blob/main/.github/CONTRIBUTING.md>`_:octicon:`link-external`

doc/source/index.rst

@@ -33,5 +33,6 @@
    fri/doc/fri
    docs/kuka_documentation
    Paper <https://arxiv.org/pdf/2311.12709>
+   contributing
    Source Code <https://github.com/lbr-stack/lbr_fri_ros2_stack/tree/humble>
    Changelog <https://github.com/lbr-stack/lbr_fri_ros2_stack/releases>