Add research notice

this helps make sure that people contributing to this repo are aware metrics will be gethered as part of the study over the next twelve months :)

Author: Yo Yehudi

README.rst

@@ -100,3 +100,20 @@ If Matplotlib contributes to a project that leads to publication, please
 acknowledge this by citing Matplotlib.
 
 `A ready-made citation entry <https://matplotlib.org/citing.html>`_ is available.
+
+Research notice
+~~~~~~~~~~~~~~~
+
+Please note that this repository is participating in a study into
+sustainability of open source projects. Data will be gathered about this
+repository for approximately the next 12 months, starting from June
+2021.
+
+Data collected will include number of contributors, number of PRs, time
+taken to close/merge these PRs, and issues closed.
+
+For more information, please visit `the informational
+page <https://sustainable-open-science-and-software.github.io/>`__ or
+download the `participant information
+sheet <https://sustainable-open-science-and-software.github.io/assets/PIS_sustainable_software.pdf>`__.
+