Add ReDoc detection (#2247)

* Add ReDoc detection

This can be tested [here](https://api.mattermost.com/#tag/APIv3-Deprecation)
The project has almost [2500 stars](https://github.com/Rebilly/ReDoc)

* Implement cools ideas from @gadcam

src/apps.json

@@ -8189,6 +8189,19 @@
       },
       "website": "http://www.redmine.org"
     },
+    "ReDoc": {
+      "cats": [
+        4
+      ],
+      "html": "<redoc ",
+      "script": "/redoc\\.(?:min\\.)?js",
+      "js": {
+        "Redoc.version": "(.*)\\;version:\\1"
+      },
+      "icon": "redoc.png",
+      "implies": "React",
+      "website": "https://github.com/Rebilly/ReDoc"
+    },
     "Reinvigorate": {
       "cats": [
         10