It's hard to believe but you can't do multiline comments in Powershell for some reason! Shame on you Microsoft! Here is a bit of a hack to allow you to right comments over multiple lines using a multiline string declaration:
@' This is a hack so you can do a multiline comment in powershell '@ > $null
Points to note...
- The closing '@ has to be in column 0
- No whitespace allowed after the opening @'
- Redirect the output (or cast to [void]) unless you want to see it on the console or in a log file