Add reference to OLED display library

Author: urmilparikh

doc/libraries.md

@@ -165,3 +165,4 @@ Libraries that don't rely on low-level access to AVR registers should work well.
 - [Dot Matrix Display Library 2](https://github.com/freetronics/DMD2) - Freetronics DMD & Generic 16 x 32 P10 style Dot Matrix Display Library
 - [SdFat-beta](https://github.com/greiman/SdFat-beta) - SD-card library with support for long filenames, software- and hardware-based SPI and lots more.
 - [FastLED](https://github.com/FastLED/FastLED) - a library for easily & efficiently controlling a wide variety of LED chipsets, like the Neopixel (WS2812B), DotStar, LPD8806 and many more. Includes fading, gradient, color conversion functions.
+- [OLED](https://github.com/klarsys/esp8266-OLED) - a library for controlling I2C connected OLED displays. Tested with 0.96 inch OLED graphics display.