add intro to linear mixed model blog post

README.md

@@ -136,6 +136,7 @@ If you are from fields outside of biology, places to get you started:
 * [Learning Statistics with R](https://learningstatisticswithr.com/)
 * [Statistical Modeling of High Dimensional Counts](https://mikelove.github.io/counts-model/) by Mike love on RNAseq counts modeling.
 * [Mixed models in R: a primer](https://arbor-analytics.com/post/mixed-models-a-primer/)
+* [Introduction to linear mixed models](https://gkhajduk.github.io/2017-03-09-mixed-models/)
 * [MIXED EFFECTS COX REGRESSION](https://stats.idre.ucla.edu/r/dae/mixed-effects-cox-regression/)
 * [mixed model/hierachical model visualized](http://mfviz.com/hierarchical-models/)