Add doc for IAR.

docs/reference/getting_started.rst

@@ -151,3 +151,39 @@ Some board use uf2 bootloader for drag & drop in to mass storage device, uf2 can
 .. code-block::
 
    $ make BOARD=feather_nrf52840_express all uf2
+
+IAR Support
+-----------
+
+IAR Project Connection files are provided to import TinyUSB stack into your project.
+
+* A buldable project of your MCU need to be created in advance.
+
+
+  * Take example of STM32F0:
+  
+    -  You need `stm32l0xx.h`, `startup_stm32f0xx.s`, `system_stm32f0xx.c`.
+
+    - `STM32L0xx_HAL_Driver` is only needed to run examples, TinyUSB stack itself doesn't rely on MCU's SDKs.
+
+* Open `Tools -> Configure Custom Argument Variables` (Switch to `Global` tab if you want to do it for all your projects) 
+   Click `New Group ...`, name it to `TUSB`, Click `Add Variable ...`, name it to `TUSB_DIR`, change it's value to the path of your TinyUSB stack,
+   for example `C:\\tinyusb`
+
+Import stack only
+^^^^^^^^^^^^^^^^^
+
+1. Open `Project -> Add project Connection ...`, click `OK`, choose `tinyusb\\tools\\iar_template.ipcf`.
+
+Run examples
+^^^^^^^^^^^^
+
+1. (Python3 is needed) Run `iar_gen.py` to generate .ipcf files of examples:
+
+   .. code-block::
+
+     cd C:\tinyusb\tools
+     python iar_gen.py
+
+2. Open `Project -> Add project Connection ...`, click `OK`, choose `tinyusb\\examples\\(.ipcf of example)`.
+   For example `C:\\tinyusb\\examples\\device\\cdc_msc\\iar_cdc_msc.ipcf`