[guide] typo in stake weighted QoS guide

[nickfrosty]

Problem

There is a typo in the sample yaml config for staked-nodes-overrides that uses stake_map where it should be staked_map_id

See: https://github.com/anza-xyz/agave/blob/21b682188511b208cae16155acc258fd1da9db0f/validator/src/admin_rpc_service.rs#L478-L495

Summary of Changes

• corrected the yaml field to staked_map_id