docs: add Zenodo DOI to CITATION.cff and README badge

Author: Nathan-D-R

CITATION.cff

@@ -29,9 +29,7 @@ keywords:
   - bioinformatics
   - Rust
   - Python
-# Zenodo DOI - filled in after first GitHub-triggered Zenodo release.
-# After Zenodo mints the concept DOI, uncomment and replace the value below:
-# identifiers:
-#   - type: doi
-#     value: "10.5281/zenodo.XXXXXXXX"
-#     description: "Concept DOI (all versions) - Zenodo"
+identifiers:
+  - type: doi
+    value: "10.5281/zenodo.20470601"
+    description: "Zenodo DOI"

README.md

@@ -1,6 +1,7 @@
 # OpenTFRaw
 
 [![CI](https://github.com/Sigilweaver/OpenTFRaw/actions/workflows/ci.yml/badge.svg)](https://github.com/Sigilweaver/OpenTFRaw/actions/workflows/ci.yml)
+[![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.20470601.svg)](https://doi.org/10.5281/zenodo.20470601)
 [![crates.io](https://img.shields.io/crates/v/opentfraw.svg)](https://crates.io/crates/opentfraw)
 [![PyPI](https://img.shields.io/pypi/v/opentfraw.svg)](https://pypi.org/project/opentfraw/)
 [![docs.rs](https://img.shields.io/docsrs/opentfraw)](https://docs.rs/opentfraw)