Update ISSUE_TEMPLATE.md

Author: mbostock

ISSUE_TEMPLATE.md

@@ -4,9 +4,9 @@ If you ignore this message and ask for help anyway, your issue will be closed wi
 
 If you want help, please try one of the following forums instead:
 
-Stack Overflow: https://stackoverflow.com/questions/tagged/d3.js
-Slack: https://d3-slackin.herokuapp.com/
-Google Groups: https://groups.google.com/d/forum/d3-js
-Observable: https://observablehq.com/@d3
+Stack Overflow: https://stackoverflow.com/questions/tagged/d3.js  
+Slack: https://d3-slackin.herokuapp.com/  
+Google Groups: https://groups.google.com/d/forum/d3-js  
+Observable: https://observablehq.com/@d3  
 
 ARE YOU REPORTING A BUG, OR MAKING A FEATURE REQUEST? Please file an issue on the relevant D3 module, not here; see https://github.com/d3. Please isolate the specific methods that exhibit unexpected behavior and precisely describe how your expectations were not met.