Update README.md
Added a link to the ONS case study in the Documentation section.
@@ -72,6 +72,8 @@ The homepage for the Splink documentation can be found [here](https://moj-analyt
The specification of the Fellegi Sunter statistical model behind `splink` is similar as that used in the R [fastLink package](https://github.com/kosukeimai/fastLink). Accompanying the fastLink package is an [academic paper](http://imai.fas.harvard.edu/research/files/linkage.pdf) that describes this model. A [series of interactive articles](https://www.robinlinacre.com/probabilistic_linkage/) also explores the theory behind Splink.
+The Office for National Statistics have written a [case study about using Splink](https://github.com/Data-Linkage/Splink-census-linkage/blob/main/SplinkCaseStudy.pdf) to link 2021 Census data to itself.
+
## Installation
Splink supports python 3.7+. To obtain the latest released version of splink:
