Add issue template.

Signed-off-by: Eric Wang <skygragon@gmail.com>

Author: skygragon

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,33 @@
+<!---
+Before submit please try followings to see if your problem is gone:
+
+1. login agian:
+```
+  leetcode login -l
+```
+
+2. run the latest code:
+```
+	cd <your local repo>
+	git pull --rebase origin master
+	./bin/install	// install globally, OR
+	./bin/leetcode <command>	// run the command locally
+```
+-->
+
+### Problem Summary
+<!--- describe what's going wrong -->
+
+### How to reproduce
+<!--- more details will help a lot, e.g.
+1. which command failed, what parameters used
+2. actual/expected output
+3. if possible, run command with "-vv" will give more outputs of the HTTP data, do REMEMBER to delete your cookies before paste here!!
+-->
+
+### Environment
+<!--- if using latest code, you could get those info in `leetcode version -v`
+-->
+- OS version:
+- Node version:
+- Npm version: