Improve the documentation with Examples

[cleder]

The documentation lacks clarity, specifically usage examples, as pointed out in various blogposts

• FastKML for Efficient Parsing of KML Files
• The Definite Guide to FastKML.
• GIS: Parsing KML file with FastKML
• FastKML on StackOverflow
• Python – Reading KML Files Using Fastkml
• Read KML files, edit items, and rewrite files?
• help needed with fastkml

[cleder]

#78 #28 #63