text: Title: Documenting tasks via docstrings
  Body: We have a feature that isn't documented, from a user:
  
  ```
  Hi, how do I define the documentation for a particular task in the pipeline? When I run ploomber status, I see the column Doc(short) which is always empty. A follow-up question is can I customize the status report ?
  ```
  
  the documentation is extracted from the docstrings (if your function is a task); alternatively, if your task is a script or a notebook, you can define a string at the top of a markdown cell. example:
  
  ```
  documentation for my script/notebook
  ```
  
  
  In case of functions that look like the following:
  ```
  def func1():
      ...
  def func2():
      ...
  if __name__ == "__main__":
      func1()
      func2()
  ```
  
  This is how you add the docstring:
  
  ```
  def func():
      """some comment"""
      ...
  ```
  
  if you want to customize the output of ploomber status you can use the Python API, you can load your pipeline with [this](https://docs.ploomber.io/en/latest/cookbook/spec-load-python.html),
  then call `dag.status()`  and then you can manipulate the object. here's the Table object that it'll return: https://github.com/ploomber/ploomber/blob/2a6287f1beea9f51ecbe59ddebac266cef6c77e8/src/ploomber/table.py#L69
  
  We should document this functionality.
  
  