Doc: update help message of --gpu-detection-method

Author: CarterLi

src/data/help.json

@@ -1199,14 +1199,14 @@
         {
             "long": "gpu-detection-method",
             "desc": "Force using a specified method to detect GPUs",
+            "remark": "Methods are used in this order: DRM (Linux only) -> PCI (Linux, FreeBSD and other platform specific methods) -> Vulkan -> OpenGL",
             "arg": {
                 "type": "enum",
-                "optional": true,
                 "enum": {
-                    "auto": "DRM (Linux only) -> PCI (Linux, FreeBSD and other platform specific methods) -> Vulkan -> OpenGL",
-                    "pci": "PCI -> Vulkan -> OpenGL",
-                    "vulkan": "Vulkan -> OpenGL",
-                    "opengl": "OpenGL"
+                    "auto": "Use DRM if available, which is most feature-rich. Requires proper DRM driver installed",
+                    "pci": "Search PCI devices, which do not requires any driver installed",
+                    "vulkan": "Use Vulkan API. Slow and requires vulkan driver installed",
+                    "opengl": "Use OpenGL API. Slow and only detects one GPU"
                 },
                 "default": "auto"
             }