Added welcome messages to discord bot

bots/discord/OnGuildMemberRemove.go

@@ -0,0 +1,14 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/bwmarrin/discordgo"
+)
+
+// OnGuildMemberRemove is called every time a user leaves the server.
+func OnGuildMemberRemove(session *discordgo.Session, event *discordgo.GuildMemberRemove) {
+	fmt.Println(event.Member.User.Username + " just left!")
+
+	// session.ChannelMessageSend(welcomeChannel, "Good bye "+event.Member.User.Mention()+"!")
+}