Update README & bump the version to 2.2.0

Author: ilia3546

Fastis.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'Fastis'
-  s.version          = '2.1.0'
+  s.version          = '2.2.0'
   s.summary          = "Simple date picker created using JTAppleCalendar library"
   s.description      = <<-DESC
   Fastis is a fully customizable UI component for picking dates and ranges created using JTAppleCalendar library.

README.md

@@ -177,6 +177,7 @@ fastisController.shortcuts = [customShortcut, .lastWeek]
 
 Fastis can be customised global or local. `FastisConfig` have some sections:
 
+- `calendar` - Base calendar that used to render UI. Default value is `.current`
 - `controller` - base view controller (`cancelButtonTitle`, `doneButtonTitle`, etc.)
 - `monthHeader` - month titles
 - `dayCell` - day cells (selection parameters, font, etc.)