Add use_psram param description to esp32_rmt_led_strip.rst (#4266)

Author: PxPert

components/light/esp32_rmt_led_strip.rst

@@ -54,6 +54,7 @@ Configuration variables
   A time interval used to limit the number of commands a light can handle per second. For example
   16ms will limit the light to a refresh rate of about 60Hz. Defaults to sending commands as quickly as
   changes are made to the lights.
+- **use_psram** (*Optional*, boolean): Set to ``false`` to force internal RAM allocation even if you have the the PSRAM component enabled. This can be useful if you're experiencing issues like flickering with your leds strip. Defaults to ``true``.
 
 - All other options from :ref:`Light <config-light>`.