[Example] add example for nextjs app and discord/slack bots (#1111)

Co-authored-by: Deven Patel <deven298@yahoo.com>

examples/nextjs/nextjs_slack/fly.toml

@@ -0,0 +1,22 @@
+# fly.toml app configuration file generated for nextjs-slack on 2024-01-05T09:33:59+05:30
+#
+# See https://fly.io/docs/reference/configuration/ for information about how to use this file.
+#
+
+app = "nextjs-slack"
+primary_region = "sjc"
+
+[build]
+
+[http_service]
+  internal_port = 8080
+  force_https = true
+  auto_stop_machines = false
+  auto_start_machines = true
+  min_machines_running = 0
+  processes = ["app"]
+
+[[vm]]
+  cpu_kind = "shared"
+  cpus = 1
+  memory_mb = 1024