Update symbol_request.md

Author: afucher

.github/ISSUE_TEMPLATE/symbol_request.md

@@ -10,9 +10,10 @@ assignees: ''
 **What is the symbol that you need?**  
 The name of the symbol/point, and if it is not a common planet/point, please describe why you need and the use of that.  
 
-**Can you contribute to this request?**
+**Can you contribute to this request?**  
 [ ] Yes, I have the svg and will add it to this issue.  
 [ ] Yes, I will open a PR with the implementation.  
+<!-- for contributing, please check our wiki about how to add a new symbol: https://github.com/AstroDraw/AstroChart/wiki/Adding-a-new-symbol-(point) -->
 
 **Additional context**  
 Add any other context or screenshots about the symbol request here.