Update index.md

Author: mtian8

docs/index.md

@@ -20,7 +20,7 @@
 
 <p align="center">
 * Equal contribution lead authors. † Data curation, alphabetical order.
-‡ Corresponding to: [mtian8](mtian8@illinois.edu), [haopeng](haopeng@illinois.edu), [elihu@anl.gov](elihu@anl.gov) <mtian8@illinois.edu>
+‡ Corresponding to: {mtian8, haopeng}@illinois.edu, elihu@anl.gov
 </p>
 
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