[docs][python] Improve documentation for xbmcdrm

[CastagnaIT]

Description

As requested from @enen92 i have tried to help to improve the documentation of this module which was too dry

Motivation and Context

Improve docu and facilitate integration

How Has This Been Tested?

Screenshots (if appropriate):

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• None of the above (please explain below)

Checklist:

• My code follows the Code Guidelines of this project
• My change requires a change to the documentation, either Doxygen or wiki
• I have updated the documentation accordingly
• I have read the Contributing document
• I have added tests to cover my change
• All new and existing tests passed

[enen92]

Awesome! Some of the lines could be a bit smaller (broken into several lines) but it's more than fine for me.
Thanks again

[enen92]

jenkins build this please

[phunkyfish]

Reads well to a native english speaker. Well done ;)