Update issue_template.md

.github/issue_template.md

@@ -1 +1,2 @@
-[//]: # (Please read guidelines in https://github.com/ocornut/imgui/blob/master/.github/CONTRIBUTING.md then delete this line)
+(Please read guidelines in https://github.com/ocornut/imgui/blob/master/.github/CONTRIBUTING.md then delete this line)
+