Add release commit hash (#85)

Author: egrace479

CITATION.cff

@@ -26,7 +26,7 @@ identifiers:
     value: "https://github.com/Imageomics/Imageomics-guide/releases/tag/v2.3.0"
   - description: "The GitHub URL of the commit tagged with v2.3.0."
     type: url
-    value: "https://github.com/Imageomics/Imageomics-guide/tree/<commit-hash>" # Update on release
+    value: "https://github.com/Imageomics/Imageomics-guide/tree/a9fa5723114f75b440c98d40dfe215da7972def6"
 keywords:
   - imageomics
   - metadata