Merge #13074: [trivial] Correct help text for importaddress RPC

Summary:
2c71edc2fc [wallet] [rpc] Fix importaddress help text (John Newbery)

Pull request description:

Help text for `importaddress` referred to the first parameter as `script`, when in fact it's `address`. Calling with a script argument fails:

```
→ bcli -named importaddress script=2N3qhMpHK8WNo7wv87W9eHMgvGyJU1593Ei
error code: -8
error message:
Unknown named parameter script
→ bcli -named importaddress address=2N3qhMpHK8WNo7wv87W9eHMgvGyJU1593Ei
# success!
```

Tree-SHA512: 24dcb2cbd0a43e25896b1c67fa0386df2453ec04d49a339e10992417b3921ce3df8a6aa5abba7d2237d6188b018948b2a21ea2f04d37120ad36c31c7b7fc9f1c

Backport of Core PR13074
https://github.com/bitcoin/bitcoin/pull/13074/

Test Plan:

make check
./bitcoind
./bitcoin-cli help importaddress

Verify the help text is changed.

Reviewers: deadalnix, Fabien, jasonbcox, O1 Bitcoin ABC, #bitcoin_abc

Reviewed By: Fabien, O1 Bitcoin ABC, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D4688