docs(README.md): add linebreak after "powered by"

README.md

@@ -312,5 +312,5 @@ Please see [this issue](https://github.com/showdownjs/showdown/issues/114) to ex
 ## Credits
 Full credit list at https://github.com/showdownjs/showdown/blob/master/CREDITS.md
 
-Showdown is powered by:
-[![webstorm](https://www.jetbrains.com/webstorm/documentation/docs/logo_webstorm.png)](https://www.jetbrains.com/webstorm/)
+Showdown is powered by:<br/>
+[![webstorm](https://www.jetbrains.com/webstorm/documentation/docs/logo_webstorm.png)](https://www.jetbrains.com/webstorm/)