chore(docs): update 11-masternode.md updatemasternode (#1921)

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#### What this PR does / why we need it:

As per the title.

docs/node/CATEGORIES/11-masternode.md

@@ -174,8 +174,8 @@ interface UTXO {
 
 ## updatemasternode
 
-Creates (and submits to local node and network) a masternode update transaction which update the masternode operator addresses, spending the given inputs..
-The last optional argument (may be empty array) is an array of specific UTXOs to spend.
+Creates a transaction to update masternode operator address, owner address, and/or reward address.
+The last optional argument (it may be an empty array) is an array of specific UTXOs to spend.
 
 ```ts title="client.masternode.updatemasternode()"
 interface masternode {