Documentation: leds: Remove .rst extension for leds-st1202 on index

No other LED driver is listed on index.rst with the extension .rst.
Remove it.

Fixes: b1816b2 ("Documentation:leds: Add leds-st1202.rst")
Signed-off-by: Manuel Fombuena <fombuena@outlook.com>
Link: https://lore.kernel.org/r/CWLP123MB5473137572529F99746F4AC4C5C32@CWLP123MB5473.GBRP123.PROD.OUTLOOK.COM
Signed-off-by: Lee Jones <lee@kernel.org>

Author: innovara

Documentation/leds/index.rst

@@ -28,5 +28,5 @@ LEDs
    leds-mlxcpld
    leds-mt6370-rgb
    leds-sc27xx
-   leds-st1202.rst
+   leds-st1202
    leds-qcom-lpg