add vulnchatters command and add comments

bot/commands/vulnchatters.ts

@@ -0,0 +1,12 @@
+import { redis } from "bun";
+import { Command, sendMessage } from ".";
+
+export default new Command('vulnchatters',
+  ['vulnchatters', 'vulnc'],
+  [],
+  async msg => {
+    const data = await redis.keys('vulnchatters:*');
+    const one = data.length === 1;
+    await sendMessage(`There ${one ? 'is' : 'are'} ${data.length} vulnerable chatter${one ? '' : 's'}`, msg.messageId);
+  }
+);