title: How to alter a column name in an Ecto model with a migration?
body: <p>Does anyone know of (or can provide) an example of how to alter a table column name using the ecto DSL</p>
  
  <p>I'm guessing I just use mix ecto.gen.migration but then would I just fill in the empty created file with my custom code (if so, how would you edit a column name, the docs show modify to change the column type)</p>
  
  <p>or is there a command line flag I can pass to generate the migration code for me?</p>