add ISSUE_TEMPLATE

.github/ISSUE_TEMPLATE

+Please answer these questions before submitting your issue. Thanks!
+
+1. What version of Go and beego are you using (`bee version`)?
+
+
+2. What operating system and processor architecture are you using (`go env`)?
+
+
+3. What did you do?
+If possible, provide a recipe for reproducing the error.
+A complete runnable program is good.
+A link on play.golang.org is best.
+
+
+4. What did you expect to see?
+
+
+5. What did you see instead?
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