text: Title: cookbook on managing multiple kernels
  Body: Sometimes is useful to execute a given script/notebook with a specific kernel, so we should add a cookbook to show how to do this. These are some quick instructions, we need help moving this to the docs.
  
  To list current kernels:
  
  ```
  jupyter kernelspec list
  ```
  
  The first column in the printed table shows the names, you can pass any of those to a script/notebook:
  
  ```yaml
    - source: fit.py
      product:
          nb: output/nb.html
          model: output/model.pickle
      kernelspec_name: some-kernel-name
  ```
  
  In some situations, you may want to have an environment to execute `ploomber build` but have the kernel run on a different one. This is possible:
  
  ```
  /path/to/kernel/env/bin/python -m ipykernel install --prefix=/path/to/jupyter/env --name 'python-my-env'
  ```
  The first argument is the Python interpreter in an arbitrary environment, while the prefix is the one where `ploomber build` is called. To find the prefix value:
  
  Activate the environment, then start Python, then:
  
  ```python
  import sys
  print(sys.prefix)
  ```
  
  More info here: https://ipython.readthedocs.io/en/6.5.0/install/kernel_install.html#kernels-for-different-environments
  
  
  
  