Docs: lambda_security_group_ids incorrect description

Howdy. Currently, the README.md has this definition for `lambda_security_group_uds`:

lambda_security_group_ids | List of subnets in which the action runners will be launched, the subnets needs to be subnets in the vpc_id.
-- | --

I think there may have been a copypasta accident with the next variable description. :) Thanks!
