Add comment about max_viewports in metal/src/device.rs
@@ -344,6 +344,9 @@ impl hal::PhysicalDevice<Backend> for PhysicalDevice {
hal::Limits {
max_texture_size: 4096, // TODO: feature set
max_patch_size: 0, // No tessellation
+
+ // Note: The maximum number of supported viewports and scissor rectangles varies by device.
+ // TODO: read from Metal Feature Sets.
max_viewports: 1,
min_buffer_copy_offset_alignment: self.private_caps.buffer_alignment,
