Fix cfg tutorials

[tristanlatr]

Here is a git error that occurs on case insensitive file systems:

warning: the following paths have collided (e.g. case-sensitive paths
on a case-insensitive filesystem) and only one from the same
colliding group is in the working tree:

  'examples/CFG_tutorial.py'
  'examples/cfg_tutorial.py'

[Jarvx]

This is due to duplicated files. Have removed. Thanks!