Update bug_report.md

.github/ISSUE_TEMPLATE/bug_report.md

@@ -7,10 +7,18 @@ assignees: ''
 
 ---
 
+**Before reporting a bug, be sure that you followed the README.md instructions.**
+
+If you still had a bug after following the instructions, please go ahead filling this template.
+
+All incomplete bug reports will be marked as 'invalid' and closed.
+
 **Describe the bug**
+
 A clear and concise description of what the bug is.
 
 **To Reproduce**
+
 Steps to reproduce the behavior:
 1. Go to '...'
 2. Click on '....'
@@ -18,19 +26,24 @@ Steps to reproduce the behavior:
 4. See error
 
 **Expected behavior**
+
 A clear and concise description of what you expected to happen.
 
 **Screenshots**
+
 If applicable, add screenshots to help explain your problem.
 
-**Smartphone (please complete the following information):**
+**Device Information:**
+
  - Device: [e.g. iPhone6]
  - OS: [e.g. iOS8.1]
  - Browser [e.g. stock browser, safari]
  - Version [e.g. 22]
  
- **Flutter**
+ **Flutter Information**
+ 
  - `flutter doctor` output
 
 **Additional context**
+
 Add any other context about the problem here.