survey: Add explicit note that survey is not actively being worked on
This commit adds a clarification about the current status of the
demographic survey, i.e. that it is not being maintained. This came up
in the D&I Team meeting because there was confusion over whether this
was a campaign/initiative we were still working towards.
cc: @riecatnor @ramyaparimi @lilyx
Signed-off-by: Justin W. Flory (he/him) <git@jwf.io>