docs: Add a section on surveys to the researcher guidelines

It is common for university researchers to want to poll the community with
online surveys, but that approach distracts developers while yielding
little in the way of useful data.  Encourage alternatives instead.

Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/87il9v7u55.fsf@meer.lwn.net