raft: Fix spelling in doc.go

raft/doc.go

@@ -87,7 +87,7 @@ large).
 
 Note: Marshalling messages is not thread-safe; it is important that you
 make sure that no new entries are persisted while marshalling.
-The easiest way to achieve this is to serialise the messages directly inside
+The easiest way to achieve this is to serialize the messages directly inside
 your main raft loop.
 
 3. Apply Snapshot (if any) and CommittedEntries to the state machine.
@@ -153,7 +153,7 @@ If the proposal is committed, data will appear in committed entries with type
 raftpb.EntryNormal. There is no guarantee that a proposed command will be
 committed; you may have to re-propose after a timeout.
 
-To add or remove node in a cluster, build ConfChange struct 'cc' and call:
+To add or remove a node in a cluster, build ConfChange struct 'cc' and call:
 
 	n.ProposeConfChange(ctx, cc)
 
@@ -260,7 +260,7 @@ stale log entries:
 	'MsgPreVote' and 'MsgPreVoteResp' are used in an optional two-phase election
 	protocol. When Config.PreVote is true, a pre-election is carried out first
 	(using the same rules as a regular election), and no node increases its term
-	number unless the pre-election indicates that the campaigining node would win.
+	number unless the pre-election indicates that the campaigning node would win.
 	This minimizes disruption when a partitioned node rejoins the cluster.
 
 	'MsgSnap' requests to install a snapshot message. When a node has just