Update ReadMe.md. added ftdi driver installation

ReadMe.md

@@ -28,6 +28,11 @@ For detailed specifications, pinout, and connection diagrams, please refer to th
   - Download the library: `svn co https://devel.iri.upc.edu/pub/labrobotica/drivers/usb_i2c_adapter/trunk usb_i2c_adapter`
   - Compile and install: `cd usb_i2c_adapter/build && cmake -D CMAKE_BUILD_TYPE=RELEASE .. && make -j $(nproc) && sudo make install`
 
+- [FTDI driver](http://www.ftdichip.com/Drivers/D2XX.htm) - (Optional)
+
+  - Download the FTDI driver depending on your ubuntu distribution: http://www.ftdichip.com/Drivers/D2XX.htm 
+  - Install the driver: http://www.ftdichip.com/Support/Documents/AppNotes/AN_220_FTDI_Drivers_Installation_Guide_for_Linux.pdf
+
 ### Installation
 
 - Clone the repository: `git clone https://gitlab.iri.upc.edu/asantamaria/LidarLite.git`