Clarification around locking (#3853)

website/source/api/kv.html.md

@@ -186,7 +186,9 @@ The table below shows this endpoint's support for
   A key does not need to exist to be acquired. If the lock is already held by
   the given session, then the `LockIndex` is not incremented but the key
   contents are updated. This lets the current lock holder update the key
-  contents without having to give up the lock and reacquire it.
+  contents without having to give up the lock and reacquire it. **Note that an update
+  that does not include the acquire parameter will proceed normally even if another
+  session has locked the key.**
 
 - `release` `(string: "")` - Specifies to use a lock release operation. This is
   useful when paired with `?acquire=` as it allows clients to yield a lock. This

website/source/docs/guides/leader-election.html.md

@@ -143,3 +143,7 @@ Clients should also watch the key using a blocking query for any
 changes. If the leader steps down or fails, the `Session` associated
 with the key will be cleared. When a new leader is elected, the key
 value will also be updated.
+
+Using the `acquire` param is optional. This means
+that if you use leader election to update a key, you must not update the key
+without the acquire parameter.