title: Triggering an Azure Devops pipeline from another pipeline
body: <p>I'm having problems triggering a pipeline from another Pipeline in Azure DevOps. I have a CI pipeline and I want to trigger a Deploy Pipeline whenever CI passes on a master branch. This seems to be <em>technically</em> possible, but the <a href="https://docs.microsoft.com/en-us/azure/devops/pipelines/build/triggers?view=azure-devops&amp;tabs=yaml#pipeline-triggers" rel="noreferrer">documentation</a> is unclear.</p>
  
  <p>I see the following:</p>
  
  <pre><code># this is being defined in app-ci pipeline
  resources:
    pipelines:
    - pipeline: securitylib
      source: security-lib-ci
      trigger: 
        branches:
        - releases/*
        - master
  </code></pre>
  
  <p>But it's unclear as to a) whether this goes in the triggering pipeline (in my case the CI pipeline) or the triggered pipeline (in my case, the deploy pipeline). </p>
  
  <p>It's also unclear as to what the <code>pipeline</code> and <code>source</code> refer to, and how I find out these variables? Are they both the name of the pipeline? I've tried various different permutations and nothing seems to be working. </p>