Fix grammar in RSS feed (plural vs singular)
Fix grammar in RSS feed (plural vs singular)

flodolo/webdashboard,pascalchevrel/webdashboard,flodolo/webdashboard,mozilla-l10n/webdashboard,mozilla-l10n/webdashboard,pascalchevrel/webdashboard,flodolo/webdashboard,mozilla-l10n/webdashboard