Update ISSUE_TEMPLATE.md

Fixing some of the language, readjusted titles, made some sections optional/recommended.

Author: bozdoz

.github/ISSUE_TEMPLATE.md

@@ -1,18 +1,17 @@
 ## Description
-Describe the issue or the enhancement you want to see in the Intro.js
+Describe one (**and only one**) issue or enhancement you want to see in Intro.js (**before writing any code**).
 
-## Environment
-All the maximum information about your environment.
-For example Intro.js version, Operating System, Node.js version, which branch, etc.
+## Expected Behavior
+What did you expect to happen?
 
-## Actual result
-What happened.
+## Actual Behavior
+What actually happened?
 
-## Expected behavior
-What should happen?
+## Errors and Screenshots (optional)
+Give us any additional information if you have.
 
-## Steps to reproduce
-How did you get?
+## Example (recommended)
+How can someone else see/test this issue?  List the steps or write some code; or create a jsfiddle or codepen.
 
-## Logs, error output, screenshots?
-Give us any additional information if you have.
+## Environment (optional)
+List browser information, Intro.js version, Operating System, JavaScript libraries (jQuery, Angular, React), etc.