Deprecation Sentry node coming

[branciard]

In October Sentry nodes will be removed. At least temporary and may be come back later :
paritytech/substrate#6845

It will force us to remove external Sentry used today before october.
We can convert the 4 external Sentry as regular passive node.
Adding more nodes to archipel chain is also better to have 2/3 consensus and tolerate more nodes down (1/3 +1) in order to orchestrate properly.

It will also force us to add security like nginx policy etc .. or remote signing if available at this time.

Web3 secure validator setup will be updated soon with new recommendations.

[branciard]

sentry cmd lines removes. proxy setups remains