do not show tips after creating the issue (#1581)

.github/ISSUE_TEMPLATE.md

-Please search your question on previous issues, [stackoverflow](https://stackoverflow.com/questions/tagged/lightgbm) or other search engines before you open a new one.
+<!--
+Please search your question on previous issues, Stack Overflow (https://stackoverflow.com/questions/tagged/lightgbm) or other search engines before you open a new one.
+-->
 
-For bugs and unexpected issues, please provide following information, so that we could reproduce on our system.
+<!--
+For bugs and unexpected issues, please provide the following information, so that we could reproduce them on our system.
+-->
 
 ## Environment info
+
 Operating System:
+
 CPU:
+
 C++/Python/R version:
 
-## Error Message:
+## Error message
+
+<!-- Paste error log here -->
 
 ## Reproducible examples
 
+<!-- Paste examples here -->
+
 ## Steps to reproduce
 
 1.