Update godoc for Staging and Promote

configuration.go

@@ -13,10 +13,9 @@ const (
 	// Nonvoter is a server that receives log entries but is not considered for
 	// elections or commitment purposes.
 	Nonvoter
-	// Staging is a server that acts like a nonvoter with one exception: once a
-	// staging server receives enough log entries to be sufficiently caught up to
-	// the leader's log, the leader will invoke a  membership change to change
-	// the Staging server to a Voter.
+	// Staging is a server that acts like a Nonvoter. A configuration change
+	// with a ConfigurationChangeCommand of Promote can change a Staging server
+	// into a Voter.
 	Staging
 )
 
@@ -95,8 +94,8 @@ const (
 	DemoteVoter
 	// RemoveServer removes a server entirely from the cluster membership.
 	RemoveServer
-	// Promote is created automatically by a leader; it turns a Staging server
-	// into a Voter.
+	// Promote changes a server from Staging to Voter. The command will be a
+	// no-op if the server is not Staging.
 	Promote
 )
 

raft.go

@@ -1370,9 +1370,7 @@ func (r *Raft) appendEntries(rpc RPC, a *AppendEntriesRequest) {
 				return
 			}
 			if entry.Term != storeEntry.Term {
-				r.logger.Warn("clearing log suffix",
-					"from", entry.Index,
-					"to", lastLogIdx)
+				r.logger.Warn("clearing log suffix", "from", entry.Index, "to", lastLogIdx)
 				if err := r.logs.DeleteRange(entry.Index, lastLogIdx); err != nil {
 					r.logger.Error("failed to clear log suffix", "error", err)
 					return