📖 Make a few bug report fields optional (ampproject#34547)

.github/ISSUE_TEMPLATE/bug-report.yml

@@ -39,37 +39,29 @@ body:
     id: browsers
     attributes:
       label: Browser(s) Affected
-      description: Specify which browser(s) are affected. Select one or more options below.
+      description: If applicable, specify which browser(s) are affected. Select one or more options below.
       multiple: true
       options:
         - Chrome
         - Firefox
         - Safari
         - Edge
         - UC Browser
-    validations:
-      required: true
   - type: input
     id: operating_systems
     attributes:
       label: OS(s) Affected
-      description: If applicable, specify which operating system(s) are affected. Otherwise just put down 'n/a'.
+      description: If applicable, specify which operating system(s) are affected.
       placeholder: e.g. Android 11
-    validations:
-      required: true
   - type: input
     id: devices
     attributes:
       label: Device(s) Affected
-      description: If applicable, specify which device(s) are affected. Otherwise just put down 'n/a'.
+      description: If applicable, specify which device(s) are affected.
       placeholder: e.g. Pixel 3
-    validations:
-      required: true
   - type: input
     id: version
     attributes:
       label: AMP Version Affected
-      description: If applicable, specify which version is affected, in the format YYMMDDHHMMXXX. Otherwise just put down 'latest'.
+      description: If applicable, specify which version is affected, in the format YYMMDDHHMMXXX.
       placeholder: e.g. 2101280515000
-    validations:
-      required: true