docs: update pm2 instructions for ES module

I had this error message, I also show what I did to fix it and added the instructions to the docs:
root@ubuntu-s-1vcpu-1gb-nyc3-01:~/ant-ride-backend/build/bin# ls
console.js  console.js.map  ecosystem.config.js  server.js  server.js.map  test.js  test.js.map

root@ubuntu-s-1vcpu-1gb-nyc3-01:~/ant-ride-backend/build/bin# pm2 start ecosystem.config.js
[PM2][ERROR] File ecosystem.config.js malformated
Error [ERR_REQUIRE_ESM]: require() of ES Module /root/ant-ride-backend/build/bin/ecosystem.config.js from /root/.nvm/versions/node/v20.13.1/lib/node_modules/pm2/lib/Common.js not supported.
ecosystem.config.js is treated as an ES module file as it is a .js file whose nearest parent package.json contains "type": "module" which declares all .js files in that package scope as ES modules.
Instead either rename ecosystem.config.js to end in .cjs, change the requiring code to use dynamic import() which is available in all CommonJS modules, or change "type": "module" to "type": "commonjs" in /root/ant-ride-backend/build/package.json to treat all .js files as CommonJS (using .mjs for all ES modules instead).

    at Common.parseConfig (/root/.nvm/versions/node/v20.13.1/lib/node_modules/pm2/lib/Common.js:331:12)
    at API._startJson (/root/.nvm/versions/node/v20.13.1/lib/node_modules/pm2/lib/API.js:934:25)
    at API.start (/root/.nvm/versions/node/v20.13.1/lib/node_modules/pm2/lib/API.js:329:12)
    at /root/.nvm/versions/node/v20.13.1/lib/node_modules/pm2/lib/binaries/CLI.js:291:13
    at /root/.nvm/versions/node/v20.13.1/lib/node_modules/pm2/node_modules/async/internal/withoutIndex.js:8:40 {
  code: 'ERR_REQUIRE_ESM'
}

root@ubuntu-s-1vcpu-1gb-nyc3-01:~/ant-ride-backend/build/bin# ls
console.js  console.js.map  ecosystem.config.js  server.js  server.js.map  test.js  test.js.map

root@ubuntu-s-1vcpu-1gb-nyc3-01:~/ant-ride-backend/build/bin# mv ecosystem.config.js ecosystem.config.cjs

root@ubuntu-s-1vcpu-1gb-nyc3-01:~/ant-ride-backend/build/bin# ls

console.js  console.js.map  ecosystem.config.cjs  server.js  server.js.map  test.js  test.js.map

root@ubuntu-s-1vcpu-1gb-nyc3-01:~/ant-ride-backend/build/bin# pm2 start ecosystem.config.cjs
[PM2][WARN] Applications web-app not running, starting...
[PM2] App [web-app] launched (1 instances)
┌────┬────────────┬─────────────┬─────────┬─────────┬──────────┬────────┬──────┬───────────┬──────────┬──────────┬──────────┬──────────┐
│ id │ name       │ namespace   │ version │ mode    │ pid      │ uptime │ ↺    │ status    │ cpu      │ mem      │ user     │ watching │
├────┼────────────┼─────────────┼─────────┼─────────┼──────────┼────────┼──────┼───────────┼──────────┼──────────┼──────────┼──────────┤
│ 0  │ web-app    │ default     │ 0.0.0   │ cluster │ 5716     │ 0s     │ 0    │ online    │ 0%       │ 43.2mb   │ root     │ disabled │
└────┴────────────┴─────────────┴─────────┴─────────┴──────────┴────────┴──────┴───────────┴──────────┴──────────┴──────────┴──────────┘
root@ubuntu-s-1vcpu-1gb-nyc3-01:~/ant-ride-backend/build/bin#
adonisjs / v6-docs

docs: update pm2 instructions for ES module #101
