Refactor DscResource.DocumentationHelper/PowerShellHelp.psm1/New-DscResourcePowerShellHelp

[PlagueHO]

Function DscResource.DocumentationHelper/PowerShellHelp.psm1/New-DscResourcePowerShellHelp has some code smells that require refactoring:

1. A lot of string concatenation which should be converted to a stringbuilder.
2. Indents being defined by a block of spaces in quotes - difficult to determine if the right number is used - should be assigned to a variable $indent = [System.String]::new(' ',4)
3. This entire block:

 $output += "    Allowed values: "
                    $property.ValueMap | ForEach-Object {
                        $output += $_ + ", "
                    }
                    $output = $output.TrimEnd(" ")
                    $output = $output.TrimEnd(",")
                    $output +=  [Environment]::NewLine

Should be replaced with:

$stringbuilder.AppendLine($indent + 'Allowed values: ' + ($property.ValueMap -join ', '))

I'm sure there are more as this code could definitely use some TLC.