Fixing broken link (#3184)

config/config.json

@@ -111,7 +111,7 @@
         "PrivacyPolicyLink": "https://about.mattermost.com/default-privacy-policy/",
         "AboutLink": "https://about.mattermost.com/default-about/",
         "HelpLink": "https://about.mattermost.com/default-help/",
-        "ReportAProblemLink": "https://about.mattermost.com/default-report-problem/",
+        "ReportAProblemLink": "https://about.mattermost.com/default-report-a-problem/",
         "SupportEmail": "feedback@mattermost.com"
     },
     "GitLabSettings": {