Merge pull request #14 from RayStick/add-DOI

Update README.md

Author: RayStick

README.md

@@ -2,6 +2,8 @@
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+[![DOI](https://zenodo.org/badge/223283087.svg)](https://zenodo.org/badge/latestdoi/223283087)
+
 PsychoPy code to display visual instructions for a _Breath Hold_ and a _Cued Deep Breathing_ task, alongside MRI scanning.
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