add docs link to readme

README.md

@@ -6,6 +6,10 @@ Matrix-free Measurement Mitigation (M3).
 
 M3 is a measurement mitigation technique that solves for corrected measurement probabilities using a dimensionality reduction step followed by either direct LU factorization or a preconditioned iterative method that nominally converges in O(1) steps, and can be computed in parallel. For example, M3 can compute corrections on 42 qubit GHZ problems in under two seconds on a quad-core machine (depending on the number of unique bitstrings in the output).
 
+## Documentation
+
+[Online Documentation @ Qiskit.org](https://qiskit.org/documentation/partners/mthree/)
+
 ## Installation
 
 You can `pip` install M3 in serial mode using PyPi via: