add temporary dev readme file for local test

IFX_README.md

@@ -0,0 +1,21 @@
+[![Build Status](https://travis-ci.org/Infineon/XMC-for-Arduino.svg?branch=master)](https://travis-ci.org/Infineon/XMC-for-Arduino)
+# Infineon's XMC Microcontroller Boards for Arduino
+
+## Local test (**ON WINDOWS**):
+
+### Clone the repository in arduino folder
+- Open Arduino and install any Infineon XMC library (e.g. 2.2.0)
+- Open the library location in Arduino program folder
+
+`C:\Users\USERNAME\AppData\Local\Arduino15\packages\Infineon\hardware\xmc`
+
+- Open git bash, type command:
+
+`git clone "HTTP_SSH_REPOSITORY" "LIBRARY_VERSION (e.g. 2.2.0)"`
+
+### Add JLink path to flasher (quick fix)
+- Open `tools/xmc-flasher.py`
+- Change line 14
+`jlinkexe = 'JLINK_EXE_PATH (e.g. C:/Program Files/SEGGER/JLink/JLink.exe)'`
+
+Refer to the main README for the rest of the usage.