Document set max_workers for Analyze_manager in code

[shchen-idmod]

Beside user can set max_workers for analyzer_manager in idmtools.ini's COMMON and block section. user can also set it in code. but set in code is different than normal platform parameter.

Code:
platform = Platform("COMPS")
am = AnayzlerManager(platform, ...., max_workers=12)

Note: we can not do this:
platform = Platform("COMPS", max_workers=12)
am = AnayzlerManager(platform, ...)

idmtools.ini

[COMMON]
# Maxium number of workers processing in parallel
max_workers = 10

[COMPS]
type        = COMPS
endpoint    = https://comps.idmod.org
environment = CALCULON
max_workers = 20

the order which max_workers to choice from: platform code > Block section > COMMON section