bert: Remove misplaced bigbird note from README

Don't write documentation tired, kids! I thought I was missing this, so
I had added it…to the wrong file, while similar notes were already
present in the file where they belonged!

bert/README.md

@@ -28,23 +28,3 @@ it.
 The list was expanded in this PR:
 
 https://github.com/caddyserver/caddy/pull/6081
-
-## SD card
-With some microSD cards, rebooting consistently leads to a boot loop. I was
-suspicious that it was all UHS microsd cards (which, these days, is most of 'em)
-based in part on information in this PR:
-https://github.com/armbian/build/pull/4824
-
-I currently have a card in there that reliably works, but I'm 90% sure that it's
-_also_ a UHS card? So I'm now really confused on what's going on. Do I have bad
-cards? Bad hardware? Bad bootloader? Bad kernel?
-
-Basically, what I've figured out is this: I have two Microcenter branded cards.
-One works every time. One never works. They contain the same contents
-(bootloader, kernel, etc). With that in mind, I guess I'm forced to conclude
-that it must be a difference in the cards. Both cards work fine for every other
-use, as far as I can tell.
-
-Anyway, I spent a fair bit of time trying to get it to work, but didn't succeed.
-After all that nonsense, I just found an SD card that happened to work reliably,
-used that one instead, and called it good enough! 🙃