[GitHub] Add prefix and label in issue template (#652)

.github/ISSUE_TEMPLATE/bug-report.yml

 name: 🐛 Bug Report
 description: Create a report to help us reproduce and fix the bug
+title: "[BUG]: "
+labels: [bug]
 
 body:
 - type: markdown

.github/ISSUE_TEMPLATE/documentation.yml

 name: 📚 Documentation
 description: Report an issue related to https://www.colossalai.org/
+title: "[DOC]: "
+labels: [documentation]
 
 body:
 - type: markdown

.github/ISSUE_TEMPLATE/feature_request.yml

 name: 🚀 Feature request
 description: Suggest an idea for this project
+title: "[FEATURE]: "
+labels: [enhancement]
 
 body:
 - type: markdown

.github/ISSUE_TEMPLATE/proposal.yml

 name: 💥 Proposal
 description: Propose a non-trivial change to Colossal-AI
+title: "[PROPOSAL]: "
+labels: [enhancement]
 
 body:
-  - type: markdown
+- type: markdown
   attributes:
     value: |
       Common reasons for proposals include:
@@ -18,14 +20,14 @@ body:
       We give you maximum freedom to write an elaborated proposal illustrating why you think the change is beneficial for us, and what steps we should take to turn this into reality.
 
 
-  - type: textarea
+- type: textarea
   attributes:
     label: Proposal
     description: A clear and concise description of what the proposal is.
   validations:
     required: true
 
-  - type: checkboxes
+- type: checkboxes
   attributes:
     label: Self-service
     description: |