Add 'chat' to the 'participate' object (#107)

* Add 'chat' to the 'participate' object

The 'chat' object if given must supply an URL form
reference to a chat for the project. Optionally
it can also supply contacts in that chat.

* Add chat.mozilla.org contribute.json to the list

Note currently it contains the IRC keys, since
Mozilla Observatory will otherwise give -5 points
until a Matrix chat room reference can be given to
point to the right Riot Web related room.

README.md

@@ -34,7 +34,16 @@ as the subject. Previous discussion can be found in the comments of [the origina
             "jgmize",
             "malexis",
             "cmore"
-        ]
+        ],
+        "chat": {
+            "url": "irc://irc.mozilla.org/#www",
+            "contacts": [
+                "pmac",
+                "jgmize",
+                "malexis",
+                "cmore"
+            ]
+        }
     },
     "bugs": {
         "list": "https://bugzilla.mozilla.org/buglist.cgi?query_format=advanced&bug_status=UNCONFIRMED&bug_status=NEW&product=www.mozilla.org",

knownurls.txt

@@ -16,3 +16,4 @@ https://raw.githubusercontent.com/mozilla/configman/master/contribute.json
 https://nightly.mozilla.org/contribute.json
 https://firefox.settings.services.mozilla.com/v1/contribute.json
 https://contrast-finder.org/contribute.json
+https://chat.mozilla.org/contribute.json

schema.json

@@ -35,6 +35,23 @@
                     "items": {
                         "type": "string"
                     }
+                },
+                "chat": {
+                  "type": "object",
+                  "properties": {
+                    "url": {
+                      "type": "string"
+                    },
+                    "contacts": {
+                      "type": "array",
+                      "items": {
+                        "type": "string"
+                      }
+                    }
+                  },
+                  "required": [
+                    "url"
+                  ]
                 }
             },
             "required": [