feat(follow): implement follow command for service status notifications

refactor(data-source): update entity and migration paths for consistency
fix(readme): update status feature notification system icon
delete(guilds): remove unused Guild entity
add(follow): create Follow entity for managing user notification preferences

src/entity/follow.entity.ts

@@ -0,0 +1,13 @@
+import { Column, Entity, PrimaryGeneratedColumn } from "typeorm";
+
+@Entity()
+export class Follow {
+    @PrimaryGeneratedColumn()
+    id: number;
+
+    @Column()
+    user_discord: string;
+
+    @Column({default: false})
+    enable: boolean;
+}