title: Different azure-pipelines.yml for different branches / environments
body: <p>I have azure-pipelines.yml in the 'develop' branch configured to trigger CI/CD after each build. But for 'release' branch I would like to have different pipeline with different flow. 
  How do I differentiate different flow in pipeline for different environments?</p>
  
  <p>This is the beginning of my file.</p>
  
  <pre><code>trigger:
  - develop
  
  pool:
    vmImage: 'ubuntu-latest'
  
  steps:
  - task: NodeTool@0
    inputs:
      versionSpec: '10.x'
    displayName: 'Install Node.js'
  </code></pre>