github icon fixed

Author: oliviakowalczyk

docs/help/index.md

@@ -6,6 +6,6 @@ If you have questions about SPM, please use the [SPM mailing list](https://www.j
 
 Before posting a question, please consult the list archives using the [search option](https://www.jiscmail.ac.uk/cgi-bin/webadmin?S1=SPM) to check if you can find a solution to your problem. 
 
-## :octicons-mark-github-24: Issues
+## :fontawesome-brands-github: Issues
 
 If you think you have discovered a problem with SPM, please report it by [creating an issue](https://github.com/spm/spm/issues/new/choose) on [GitHub](https://github.com/spm).