docs(usb): Update links and example checks

Replace the peripherals index USB entries with direct links to
ESP-USB so the generated pages are no longer redirect-only stubs.

Keep legacy USB URLs working via redirects, including the
individual USB host maintainer notes pages.

Remove the obsolete placeholder documents and stale CODEOWNERS
pattern.

Mark the moved USB examples as KNOWN_MISSING in the example
documentation checker until it can also read the ESP-USB guide.

docs/en/api-reference/peripherals/index.rst

@@ -49,7 +49,7 @@ Peripherals API
     :SOC_TOUCH_SENSOR_SUPPORTED: cap_touch_sens
     :SOC_TWAI_SUPPORTED: twai
     uart
-    :SOC_USB_OTG_SUPPORTED: usb_device
-    :SOC_USB_OTG_SUPPORTED: usb_host
+    :SOC_USB_OTG_SUPPORTED: USB Device Stack <https://docs.espressif.com/projects/esp-usb/en/latest/{IDF_TARGET_PATH_NAME}/usb_device.html>
+    :SOC_USB_OTG_SUPPORTED: USB Host <https://docs.espressif.com/projects/esp-usb/en/latest/{IDF_TARGET_PATH_NAME}/usb_host.html>
 
 Code examples for this API section are provided in the :example:`peripherals` directory of ESP-IDF examples.

docs/en/api-reference/peripherals/usb_device.rst

@@ -1,6 +0,0 @@
-USB Device Stack
-================
-
-:link_to_translation:`zh_CN:[中文]`
-
-USB Device documentation has moved to `ESP-USB <https://docs.espressif.com/projects/esp-usb/en/latest/{IDF_TARGET_PATH_NAME}/usb_device.html>`_.

docs/en/api-reference/peripherals/usb_host.rst

@@ -1,6 +0,0 @@
-USB Host
-========
-
-:link_to_translation:`zh_CN:[中文]`
-
-USB Host documentation has moved to `ESP-USB <https://docs.espressif.com/projects/esp-usb/en/latest/{IDF_TARGET_PATH_NAME}/usb_host.html>`_.