Update issue templates

.github/ISSUE_TEMPLATE/feature-requests.md

 ---
 name: Feature Requests
 about: Suggest an idea for Tensorpack
+title: ''
+labels: ''
+assignees: ''
 
 ---
 

.github/ISSUE_TEMPLATE/unexpected-problems---bugs.md

 ---
 name: Unexpected Problems / Bugs
 about: Report unexpected problems about Tensorpack or its examples.
+title: Please read & provide the following information
+labels: ''
+assignees: ''
 
 ---
 

.github/ISSUE_TEMPLATE/using-understanding-tensorpack.md

 ---
 name: Using/Understanding Tensorpack
 about: More general questions about Tensorpack.
+title: ''
+labels: ''
+assignees: ''
 
 ---