[TYPO3-ect] some documentation about the switch

[Fabien Udriot]

Could you provide some documentation about the "switch" concept ? In the 
documentation in the lib/doc/manual.txt there are little lines about this.

As I understand, it is a way to select the right controller according 
some context. Can you tell a bit more ?

For example, can I choose a specific controller depending on the url 
parameter ?

index.php?controller=xxxxx