adr: Amend decisions for PrivValidator

docs/architecture/adr-008-priv-validator.md

@@ -31,10 +31,15 @@ Tendermint node's should support only two in-process PrivValidator implementatio
 The PrivValidatorSocket address can be provided via flags at the command line -
 doing so will cause Tendermint to ignore any "priv_validator.json" file and to listen
 on the given address for incoming connections from an external priv_validator process.
+It will halt any operation until at least one external process succesfully
+connected.
 
 The external priv_validator process will dial the address to connect to Tendermint,
 and then Tendermint will send requests on the ensuing connection to sign votes and proposals.
 Thus the external process initiates the connection, but the Tendermint process makes all requests.
+In a later stage we're going to support multiple validators for fault
+tolerance. To prevent double signing they need to be synced, which is deferred
+to an external solution (see #1185).
 
 In addition, Tendermint will provide implementations that can be run in that external process.
 These include: