Remove mentions of rmt_channel from esp32_rmt_led_strip (#5217)

This was supposed to have gone away already but was accidentally left behind.

https://discord.com/channels/429907082951524364/1403088738560774214/1403092458337992856

Delete it.

Author: pzich

components/light/esp32_rmt_led_strip.rst

@@ -17,14 +17,6 @@ This is a component using the ESP32 RMT peripheral to drive most addressable LED
         chipset: ws2812
         name: "My Light"
 
-Only for Arduino platforms (and ESP-IDF <5 which was used until ESPHome 2025), the RMT channel must be defined.
-
-.. code-block:: yaml
-
-    light:
-      - platform: esp32_rmt_led_strip
-        ...
-
 Configuration variables
 -----------------------