Fix typo in LedStrip.md

[DusKing1]

Doc typo fix.

[asizon]

wow good catch @DusKing1 . Does this line should be also 32 and not 12?
https://github.com/betaflight/betaflight/blob/d3869e4d97d739d539e234190fceb6df17959eeb/docs/LedStrip.md#example-12-led-config

[haslinghuis]

Also good catch @asizon but I think the number should be 28. The last 4 LED aren't used in the example. But there is a second 28 Led example in the text. So not sure how to name this?

[asizon]

True @haslinghuis , seems that 28 Leds example is designed for Alien Spider AQ50D PRO 250mm frame. Maybe we need to fix 12 Led example removing info from 12 to 28 leds and make a separate example for this default 28 Leds example

[haslinghuis]

Or label the first 12 LEDs example as Default config with 28 LEDs and rename the second Exmple 28 LED config as Alien Spider 28 LED configuration .