Move issue template to '.github' folder and add some styling for better readability

.github/issue_template.md

@@ -0,0 +1,7 @@
+<!-- Do you have a question? Please ask it on https://stackoverflow.com/questions/tagged/monaco-editor -->
+**monaco-editor version:** 0.X.Y
+**Browser:**
+**OS:** 
+
+**Steps or JS usage snippet reproducing the issue:**
+

ISSUE_TEMPLATE

@@ -1,5 +0,0 @@
-<!-- Do you have a question? Please ask it on https://stackoverflow.com/questions/tagged/monaco-editor -->
-monaco-editor version: 0.X.Y
-Browser:
-OS: 
-Steps or JS usage snippet reproducing the issue: