Add info about printf

README.md

@@ -12,8 +12,8 @@ If you're into "generic" AVR programming, I'm happy to tell you that all relevan
 * [Bootloader option](#bootloader-option)
 * [BOD option](#bod-option)
 * [Link time optimization / LTO](#link-time-optimization--lto)
+* [Printf support](#printf-support)
 * [Programmers](#programmers)
-* [Why add Arduino support for these microcontrollers?](#why-add-arduino-support-for-these-microcontrollers)
 * [Write to own flash](#write-to-own-flash)
 * **[How to install](#how-to-install)**
 	- [Boards Manager Installation](#boards-manager-installation)
@@ -46,14 +46,6 @@ Can't decide what microcontroller to choose? Have a look at the specification ta
 <b>*</b> ATmega328PB has 9 PWM pins
 
 
-## Why add Arduino support for these microcontrollers?
-* They are all Arduino UNO compatible (drop-in replacement)
-* They're extremely popular and used in many Arduino project out there
-* They're cheap (some can be bought for less than a dollar on AliExpress and Ebay)
-* They come in DIP, TQFP and QFN packages
-* You can now choose the suited microcontroller for your project. No need to go for overkill!
-
-
 ## Supported clock frequencies
 MiniCore supports a variety of different clock frequencies. Select the microcontroller in the boards menu, then select the clock frequency. You'll have to hit "Burn bootloader" in order to set the correct fuses and upload the correct bootloader.  
 Make sure you connect an ISP programmer, and select the correct one in the "Programmers" menu. For time critical operations an external crystal/oscillator is recommended.  
@@ -103,6 +95,12 @@ After Arduino IDE 1.6.11 where released, There have been support for link time o
 I encourage you to try the new LTO option and see how much smaller your code gets! Note that you don't need to hit "Burn Bootloader" in order to enable LTO. Simply enable it in the "Tools" menu, and your code is ready for compilation. If you want to read more about LTO and GCC flags in general, head over to the [GNU GCC website](https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html)!
 
 
+## Printf support
+Unlike the official Arduino cores, MiniCore has printf support out of the box. If you're not familiar with printf you should probably [read this first](https://www.tutorialspoint.com/c_standard_library/c_function_printf.htm). It's added to the Print class and will work with all libraries that inherit Print. Printf is a standard C function that lets you format text much easier than using Arduino's built-in print and println. Note that this implementation of printf will NOT print floats or doubles. This is a limitation of the avr-libc printf implementation on AVR microcontrollers, and nothing I can easily fix.
+
+If you're using a serial port, simply use `Serial.printf("Milliseconds since start: %ld\n", millis());`. Other libraries that inherit the Print class (and thus supports printf) are the LiquidCrystal LCD library and the U8G2 graphical LCD library.
+
+
 ## Programmers
 MiniCore does not adds its own copies of all the standard programmers to the "Programmer" menu. Just select one of the stock programmers in the "Programmers" menu, and you're ready to "Burn Bootloader" or "Upload Using Programmer".