custom contribution type for apps [skip ci]

.all-contributorsrc

@@ -2,6 +2,13 @@
   "files": [
     "README.md"
   ],
+  "types": {
+    "app": {
+      "symbol": "📦",
+      "description": "Contributed by adding apps to Tipi.",
+      "link": "[<%= symbol %>](<%= url %> \"<%= description %>\"),"
+    }
+  },
   "imageSize": 100,
   "commit": false,
   "contributors": [
@@ -14,7 +21,8 @@
         "code",
         "infra",
         "test",
-        "doc"
+        "doc",
+        "app"
       ]
     },
     {