Update Imperva detection

- Add x-cdn header
- Add CDN category
- Add product description

src/technologies/i.json

@@ -392,10 +392,13 @@
   },
   "Imperva": {
     "cats": [
-      16
+      16,
+      31
     ],
+    "description": "Imperva is a cyber security software and services company for networking, data, and application security.",
     "headers": {
-      "X-Iinfo": ""
+      "X-Iinfo": "",
+      "x-cdn": "^Imperva"
     },
     "icon": "Imperva.svg",
     "scriptSrc": [