[Asterisk-doc] Outline addition: Planing the dimensions

[Philipp von Klitzing]

chapter: Installing Asterisk
sub: Planning an Asterisk-based system (insert before Requirements)

This should provide a set of basic questions like:
- how many internal extension/ users?
- how many external lines
- how many concurrent calls?
- what level of redundancy & uptime?
- how to provide emergency (911 or 110/112 in Europe)?
- what codecs will be used?
- heavy IVR use or call center planned?
- does LAN provide support for QoS?

What follows are calculation rules e.g. for codec bandwidth, possibly 
also CPU strength, RAM and PCI bus speeds (?).

Cheers, Philipp