Addred a README.md file

README.md

@@ -1,6 +1,9 @@
 # Similarity Estimation via Tensor Sketching
 This repository contains the reference implementation for the Tensor Sketching method, which can be used to estimate sequence similarity without needing to align the sequences.
 
+The method is described in the paper by Amir Joudaki et al. [`Fast Alignment-Free Similarity Estimation By Tensor
+ Sketching`](https://www.biorxiv.org/content/10.1101/2020.11.13.381814v1.full).
+
 ## Download and build
 ```
 git clone https://github.com/ratschlab/Project2020-seq-tensor-sketching