feat: add cache env to env example

Author: shakkernerd

.env.example

@@ -1,3 +1,7 @@
+# Cache Configs
+CACHE_STORE=database # Defaults to database. Other available cache store: redis and filesystem
+REDIS_URL= # Redis URL - could be a local redis instance or cloud hosted redis. Also support rediss:// urls
+
 # Discord Configuration
 DISCORD_APPLICATION_ID=
 DISCORD_API_TOKEN=              # Bot token