Added pdf link

README.md

@@ -9,4 +9,6 @@ This project aims to implement FPGA gateware that can:
 In one shot, up to 1023 programmable frequencies can be measured, and the excitation signal is ramped adiabatically between the different frequencies. 
 The extracted cos/sin components for each of the requested frequencies is stored in BRAM and can be streamed back to the controlling PC.
 
-Ringup times, dwell times and ramp speeds are individually programmable.
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+Ringup times, dwell times and ramp speeds are individually programmable.
+
+For more information on the design of the system, see [design/stitch_design.pdf](design/stitch_design.pdf)
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