The RPC docs are now enforced to specify the json type of the args and results at compile time. However, some help texts contain the type twice. (E.g. https://github.com/bitcoin/bitcoin/pull/17809#discussion_r386295217 ). The duplicate type in the description should be removed.

Duplicates can be found with this command:

```sh
git grep --extended-regexp  'RPC.*(ARR|OBJ).*json (array|object)' src/rpc/ src/wallet/rpc*
```

#### Useful skills:

Basic understanding of how to compile and run Bitcoin Core.

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{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    const CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
            RPCHelpMan{"getbalance",
                "\nReturns the total available balance.\n"
                "The available balance is what the wallet considers currently spendable, and is\n"
                "thus affected by options which limit spendability such as -spendzeroconfchange.\n",
                {
                    {"dummy", RPCArg::Type::STR, RPCArg::Optional::OMITTED_NAMED_ARG, "Remains for backward compatibility. Must be excluded or set to \"*\"."},
                    {"minconf", RPCArg::Type::NUM,  "0", "Only include transactions confirmed at least this many times."},
                    {"include_watchonly", RPCArg::Type::BOOL,  "true for watch-only wallets, otherwise false", "Also include balance in watch-only addresses (see 'importaddress')"},
                    {"avoid_reuse", RPCArg::Type::BOOL,  "true", "(only available if avoid_reuse wallet flag is set) Do not include balance in dirty outputs; addresses are considered dirty if they have previously been used in a transaction."},
                },
                RPCResult{