Add commercial licence and update config files

LICENSE-COMMERCIAL

@@ -0,0 +1,6 @@
+Licensees holding a valid commercial license with Element may use this
+software in accordance with the terms contained in a written agreement
+between you and Element.
+
+To purchase a commercial license please contact our sales team at
+licensing@element.io

contribute.json

@@ -3,7 +3,7 @@
     "description": "A glossy Matrix collaboration client for the web.",
     "repository": {
         "url": "https://github.com/element-hq/element-web",
-        "license": "AGPL-3.0-only OR GPL-3.0-only"
+        "license": "AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial"
     },
     "bugs": {
         "list": "https://github.com/element-hq/element-web/issues",

package.json

@@ -7,7 +7,7 @@
         "type": "git",
         "url": "https://github.com/element-hq/element-web"
     },
-    "license": "AGPL-3.0-only OR GPL-3.0-only",
+    "license": "AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial",
     "files": [
         "lib",
         "res",