Fix typo in alt text in README

Author: amorison

README.rst

@@ -12,7 +12,7 @@
 
 .. image:: https://zenodo.org/badge/DOI/10.5281/zenodo.5512348.svg
    :target: https://doi.org/10.5281/zenodo.5512348
-   :alt: DIO on zenodo
+   :alt: DOI on zenodo
 
 StagPy
 ======