Merge bitcoin/bitcoin#29308: doc: update BroadcastTransaction comment

31cce4a doc: update `BroadcastTransaction` comment (ismaelsadeeq)

Pull request description:

  `BroadcastTransaction` is also called by `submitpackage` RPC.

  All transactions that are accepted into the mempool post package processing are broadcasted to peers individually here
  https://github.com/bitcoin/bitcoin/blob/ea4ddd8652d9dd1e7698e2a6f84c606cf24a2e3e/src/rpc/mempool.cpp#L926

  It's not maintainable to list all the callers of a function.

ACKs for top commit:
  stickies-v:
    ACK 31cce4a
  kristapsk:
    ACK 31cce4a
  naumenkogs:
    ACK 31cce4a

Tree-SHA512: 8aea92c53c1911a0ac36fe9e3a24d37d83e7d9b40a16f0832bfa7a719328697621e3f94a5dc80d1840e7ae705e0c3aab7a3df7064986e1e53a4a4114adf078a8

src/node/transaction.cpp

@@ -32,7 +32,7 @@ static TransactionError HandleATMPError(const TxValidationState& state, std::str
 
 TransactionError BroadcastTransaction(NodeContext& node, const CTransactionRef tx, std::string& err_string, const CAmount& max_tx_fee, bool relay, bool wait_callback)
 {
-    // BroadcastTransaction can be called by either sendrawtransaction RPC or the wallet.
+    // BroadcastTransaction can be called by RPC or by the wallet.
     // chainman, mempool and peerman are initialized before the RPC server and wallet are started
     // and reset after the RPC sever and wallet are stopped.
     assert(node.chainman);