title: Add column to table with Liquibase
body: <p>I'm new to back-end development and currently trying to add a column to my app_user table. like below.</p>
  
  <pre><code>- changeSet:
        id: 300520202335
        author: Malindu De Alwis
        changes:
          - addColumn:
              tableName: app_user
                columns:
                -column:
                  name: address
                  type: VARCHAR(255)
  </code></pre>
  
  <p>It gives this error</p>
  
  <pre><code>Caused by: org.yaml.snakeyaml.scanner.ScannerException: mapping values are not allowed here
  </code></pre>
  
  <p>in 'reader', line 23, column 22:
                    columns:
                           ^</p>
  
  <p>I use Spring boot and postgre sql. Please try to figureout the issue</p>