Make issue template headers semantic (#152)

Closes #150

.github/ISSUE_TEMPLATE/bug_report.md

@@ -4,26 +4,26 @@ about: Report an issue or a bug after you have searched through existing issues
 
 ---
 
-**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.
 
-**Desktop (please complete the following information):**
+#### Desktop (please complete the following information):
  - OS: [e.g. iOS]
  - Browser [e.g. chrome, safari]
  - Version [e.g. 22]
 
-**Additional context**
+#### Additional context
 Add any other context about the problem here.

.github/ISSUE_TEMPLATE/feature_request.md

@@ -4,14 +4,14 @@ about: Suggest a challenge or a feature for this project
 
 ---
 
-**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.