design: cover all disabilities in Code of Conduct, not just physical ones
design: cover all disabilities in Code of Conduct, not just physical ones

Change-Id: Iabf9b94fe260145aeb8df85e3b811eb60831e3c6
Reviewed-on: https://go-review.googlesource.com/17163
Reviewed-by: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>

golang/proposal,golang/proposal