adjusted composer.json links

composer.json

@@ -5,11 +5,11 @@
     "type": "yii2-extension",
     "license": "BSD-3-Clause",
     "support": {
-        "issues": "https://github.com/yiisoft/yii2/issues?labels=ext%3Aswiftmailer",
+        "issues": "https://github.com/yiisoft/yii2-swiftmailer/issues",
         "forum": "http://www.yiiframework.com/forum/",
         "wiki": "http://www.yiiframework.com/wiki/",
         "irc": "irc://irc.freenode.net/yii",
-        "source": "https://github.com/yiisoft/yii2"
+        "source": "https://github.com/yiisoft/yii2-swiftmailer"
     },
     "authors": [
         {