feat: add documentation to readthedocs

Author: DiogoRibeiro7

README.md

@@ -1,6 +1,7 @@
 # gen_surv
 
 ![Coverage](https://codecov.io/gh/DiogoRibeiro7/genSurvPy/branch/main/graph/badge.svg)
+[![Docs](https://readthedocs.org/projects/gensurvpy/badge/?version=latest)](https://gensurvpy.readthedocs.io/en/latest/)
 
 **gen_surv** is a Python package for simulating survival data under a variety of models, inspired by the R package [`genSurv`](https://cran.r-project.org/package=genSurv). It supports data generation for: