Update issue templates

Update the section formatting of all templates

Add the contribution possibility question to the `Bug report` type

.github/ISSUE_TEMPLATE/bug_report.md

@@ -7,28 +7,34 @@ assignees: ''
 
 ---
 
-**Describe the bug**
+### Describe the bug
 A clear and concise description of what the bug is.
 
-**To Reproduce**
+### To Reproduce
 Steps to reproduce the behavior:
 1. Go to '...'
 2. Click on '....'
 3. Scroll down to '....'
 4. See error
 
-**Expected behavior**
+### Expected behavior
 A clear and concise description of what you expected to happen.
 
-**Screenshots**
+### Screenshots
 If applicable, add screenshots to help explain your problem.
 
-**Environment software versions (please complete the following information):**
+### Environment software versions (please complete the following information):**
  - OS: [e.g. Ubuntu Server 20.04.6]: 
  - kernel version [e.g. v5.4.0-200-generic]: 
  - free5GC version [e.g. v3.4.4]: 
  - BASH version [e.g. 5.0.17]: 
  - Tool version [e.g. v1.2.0]: 
 
-**Additional context**
+### Additional context
 Add any other context about the problem here.
+
+### Contribution possibility
+Do you have the possibility of contributing code with your request (e.g. with a PR)? (Choose one of the options below and delete the others)
+[ ] Yes, I know where to start and I have time to contribute a PR
+[ ] Yes, I know where to start but I don't have time to contribute a PR
+[ ] No, I don't know where to start and I don't have time to contribute a PR

.github/ISSUE_TEMPLATE/feature_request.md

@@ -7,19 +7,19 @@ assignees: ''
 
 ---
 
-**Is your feature request related to a problem? Please describe.**
+### Is your feature request related to a problem? Please describe.
 A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
 
-**Describe the solution you'd like**
+### Describe the solution you'd like
 A clear and concise description of what you want to happen.
 
-**Describe alternatives you've considered**
+### Describe alternatives you've considered
 A clear and concise description of any alternative solutions or features you've considered.
 
-**Additional context**
+### Additional context
 Add any other context or screenshots about the feature request here.
 
-**Contribution possibility**
+### Contribution possibility
 Do you have the possibility of contributing code with your request (e.g. with a PR)? (Choose one of the options below and delete the others)
 [ ] Yes, I know where to start and I have time to contribute a PR
 [ ] Yes, I know where to start but I don't have time to contribute a PR