Fix Add-DnsServerResourceRecord TXT Records Limit
When attempting to add a TXT DNS record via the "Add-DnsServerResourceRecord" command, the DescriptiveText property only accepts strings up to 254 characters but should support up to 255 characters. Ideally the command should accept an array for the DescriptiveText so that multiple lines of up to 255 characters can be passed through. Currently it requires using `r`n to insert a line break but over all must still be under 254 characters. This is an issue as we are trying to implement automation around TXT records and DKIM records tend to be well over this 254 character limit and require multiple lines.