4e05687153 [wallet] [rpc] [doc] importprivkey: hint about importmulti (Karl-Johan Alm)
Pull request description:
From #12701, a hint about `importmulti` inside the help for `importprivkey` seems useful.
Tree-SHA512: 09ddfd384062b4365f678167076cb9f5af1eb8f083714a20c2a9bb14fef1c886d1666196272bf09862537166d15ae89c3330cdc6836eee76cb54d137e53301df
Backport of Core PR12702
https://github.com/bitcoin/bitcoin/pull/12702/