Wrong parser API usage for mqtt and amqp

[Tenischev]

Describe the bug

Due to following errors in API usage generation falls down:
.bindings('amqp') instead of .binding('amqp')
.bindings('mqtt') instead of .binding('mqtt')
variables(port) instead of variable('port')

How to Reproduce

Run with

servers:
  production:
    url: api.streetlights.smartylighting.com:{port}
    protocol: mqtt
    description: Test broker
    variables:
      port:
        description: Secure connection (TLS) is available through port 8883.
        default: '1883'
        enum:
          - '1883'
          - '8883'

Expected behavior

Template generates without errors

[asyncapi-bot]

🎉 This issue has been resolved in version 0.5.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀