Add details to the roadmap section
Mention the release cycle and add links to deprecation issues/PRs.
Roadmap
*******
-cocotb is in active development.
+cocotb is under development;
+however there is no "master plan".
+We depend upon users to contribute new features and improvements
+while maintainers focus mostly on reviewing PRs, project management, and bugfixes.
+Releases will occur approximately every 6 months.
We use GitHub issues to track our pending tasks.
Take a look at the `open feature list <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+is%3Aopen+label%3Atype%3Afeature>`_ to see the work that's lined up,
or the `list of good first issues <https://github.com/cocotb/cocotb/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22>`_ to get your feet wet.
If you have a GitHub account you can also `raise an enhancement request <https://github.com/cocotb/cocotb/issues/new>`_ to suggest new features.
+
+You may be interested in discussions about `planned deprecations <https://github.com/cocotb/cocotb/issues?q=is%3Aopen+label%3Atype%3Adeprecation>`_
+or review the `list of already applied deprecations <https://github.com/cocotb/cocotb/issues?q=is%3Aclosed+label%3Atype%3Adeprecation>`_.
