feat(DOI): introduce DOI into CITATION and README

CITATION.cff

@@ -32,3 +32,10 @@ keywords:
 license: MIT
 version: 0.16.0
 date-released: '2023-01-17'
+identifiers:
+  - description: >-
+      This is the general DOI to cite all versions of the software. To cite a specific
+      version, please check the README or the Zenodo webpage.
+    type: doi
+    value: "10.5281/zenodo.7552895"
+

README.md

@@ -3,8 +3,7 @@
 [![pipeline status](https://gitlab1.ptb.de/ludwig10_masters_thesis/gum-compliant_neural-network_uncertainty-propagation/badges/main/pipeline.svg)](https://gitlab1.ptb.de/ludwig10_masters_thesis/gum-compliant_neural-network_uncertainty-propagation/-/commits/main)
 [![coverage report](https://gitlab1.ptb.de/ludwig10_masters_thesis/gum-compliant_neural-network_uncertainty-propagation/badges/main/coverage.svg)](https://gitlab1.ptb.de/ludwig10_masters_thesis/gum-compliant_neural-network_uncertainty-propagation/-/commits/main)
 [![Latest Release](https://img.shields.io/github/v/release/BjoernLudwigPTB/pytorch_gum_uncertainty_propagation?label=Latest%20release)](https://github.com/BjoernLudwigPTB/pytorch_gum_uncertainty_propagation/releases/latest)
-[![Documentation Status](https://readthedocs.org/projects/pytorch-gum-uncertainty-propagation/badge/?version=latest)](https://pytorch-gum-uncertainty-propagation.readthedocs.io/en/latest/?badge=latest)
-
+[![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.7552896.svg)](https://doi.org/10.5281/zenodo.7552896)
 
 This is the code written in conjunction with the first part of my Master's thesis on 
 GUM-compliant neural network robustness verification. The code was written for