Documented the currently implemented tasks provided with Bolt

[CurroRodriguez]

Description

Added documentation to the first tasks provided with Bolt. The documentation includes the following tasks:

• delete-files. Used to delete files in a project tree.
• delete-pyc. Used to delete .pyc files in a project tree.
• pip. Used to automate pip.
• setup. Used to automate setup.py functionality.
• shell. Used to execute a shell command.