Update issue templates

.github/ISSUE_TEMPLATE/bug_report.md

@@ -9,10 +9,12 @@ assignees: vpenades
 
 **Before submitting a bug**
 
-It is fairly common that loading issues are produced by _malformed_ glTF files, so **YOU MUST** check the model you're trying to load with [glTF Validator](https://github.khronos.org/glTF-Validator/) before submitting a bug report.
+It is fairly common that loading issues are produced by malformed glTF files, so YOU MUST check the model you're trying to load with glTF Validator before submitting a bug report.
 
-- If [glTF Validator](https://github.khronos.org/glTF-Validator/) reports the model has errors, then you must report the problem to the owner of the exporter, _not here_.
-- If [glTF Validator](https://github.khronos.org/glTF-Validator/) reports no erros, then you can proceed to report the issue here.
+    https://github.khronos.org/glTF-Validator
+
+- If glTF Validator reports the model has errors, then you must report the problem to the owner of the exporter, _not here_.
+- If glTF Validator reports no errors, then you can proceed to report the issue here.
 
 **Describe the bug**
 A clear and concise description of what the bug is.