Set `white-space: pre-wrap` to first td of quotes and invoices

It is common to want to enumerate in a description, for instance when
adding specifications for a hosting, and that enumeration should be
formatted as the user wrote, otherwise it becomes useless.

Closes #94.

web/static/invoice.css

@@ -99,6 +99,7 @@
 
 .invoice tbody td:first-child {
     max-width: 15em;
+    white-space: pre-wrap;
 }
 
 .invoice .legal {