issue template: fix order (same as in PR template)

Author: 0xc0170

.github/issue_template.md

@@ -1,5 +1,17 @@
-### Issue request type
+### Description
+<!-- 
+    Required
+    Add detailed description of what you are reporting.
+    Good example: https://os.mbed.com/docs/latest/reference/workflow.html
+    Things to consider sharing:
+    - What target does this relate to?
+    - What toolchain are you using?
+    - What is the SHA of Mbed OS (git log -n1 --oneline)?
+    - Steps to reproduce. (Did you publish code or a test case that exhibits the problem?)
+-->
+
 
+### Issue request type
 <!-- 
     Required
     Please add only one X to one of the following types. Do not fill multiple types. (Split the issue otherwise.)
@@ -16,14 +28,3 @@
 [ ] Enhancement  
 [ ] Bug  
 
-<!-- 
-    Required
-    Add detailed description of what you are reporting.
-    Good example: https://os.mbed.com/docs/latest/reference/workflow.html
-    Things to consider sharing:
-    - What target does this relate to?
-    - What toolchain are you using?
-    - What is the SHA of Mbed OS (git log -n1 --oneline)?
-    - Steps to reproduce. (Did you publish code or a test case that exhibits the problem?)
--->
-### Description