Add blacklist for unwanted tag names

Close #4

src/NodaTagBlacklist.php

@@ -0,0 +1,22 @@
+<?PHP
+/**
+ * Constains a list of disallowed tags.
+ *
+ * @author Joshua Ramon Enslin <joshua@jrenslin.de>
+ */
+declare(strict_types = 1);
+
+/**
+ * Provides a list of disallowed tags.
+ */
+final class NodaTagBlacklist {
+
+    const BLACKLIST = [
+        'de' => [
+            'Sonst.',
+            'Sonstige',
+            'Sonstiges',
+        ],
+    ];
+
+}