Update composer suggestions

Author: MarkBaker

composer.json

@@ -72,8 +72,8 @@
     },
     "suggest": {
         "mpdf/mpdf": "Option for rendering PDF with PDF Writer",
-        "dompdf/dompdf": "Option for rendering PDF with PDF Writer",
-        "tecnickcom/tcpdf": "Option for rendering PDF with PDF Writer",
+        "dompdf/dompdf": "Option for rendering PDF with PDF Writer (doesn't yet support PHP8)",
+        "tecnickcom/tcpdf": "Option for rendering PDF with PDF Writer (doesn't yet support PHP8)",
         "jpgraph/jpgraph": "Option for rendering charts, or including charts with PDF or HTML Writers"
     },
     "autoload": {