Upgrades the project Code of Conduct from Contributor Covenant v1.4
(2016) to v2.1 (2021). v2.1 adds the Enforcement Guidelines section
(Correction / Warning / Temporary Ban / Permanent Ban) and modernizes
the language around inclusion and community leadership.
Replaces the personal reporting address (lorenz@px4.io) with an
institutional one (coc@dronecode.org) so Code of Conduct reports flow
to the Dronecode Foundation rather than a single maintainer's inbox.
Signed-off-by: Ramon Roche <mrpollo@gmail.com>
