update readme

Author: ncborcherding

README.md

@@ -9,7 +9,7 @@ API for single-cell immune repertoire deep learning models
 [![Bioc Downloads](http://www.bioconductor.org/shields/downloads/release/immApex.svg)](http://bioconductor.org/packages/stats/bioc/immApex/)
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-<img align="right" src="https://github.com/BorchLab/immApex/blob/main/www/immApex_hex.png" width="305" height="352">
+<img align="right" src="https://github.com/BorchLab/immApex/blob/devel/www/immApex_hex.png" width="305" height="352">
 
 ### Introduction