* README.md: expand credit for original
Sudo was invented on Berkeley Unix on a VAX, and the current version is maintained by Todd Miller of the OpenBSD Unix project. It is thus correct to refer to the original as Unix/Linux as it is not a project originated by the Linux developers.
* Update README.md again, in ref to original sudo
Suggested by "omni" to have 'less occurrences of "Unix/Linux" in the README' - reads better this way.
Fixed $null comparison for consistency and corrected a code typo, but I'm **unsure if it introduces new issues or solves them**.
`$sudoOffet` ➡️ `$sudoOffset`
```
$sudoOffset = $cmdLine.IndexOf($MI.InvocationName)
$cmdLineWithoutScript = $cmdLine.SubString($sudoOffset + 5) # Typo was here
```
Also removed unused line of code `$iam = $MI.MyCommand.ToString()`. This might be used for debugging?
Mike Griese