HACKING: Clarify braces in if-else

Document common practice in the other files.
3 jobs for if-else-braces in 3 minutes and 16 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #4483
librem5
build-debian-clang

00:01:59

passed #4482
librem5
build-debian-gcc

00:01:44

25.4%
passed #4484
librem5
build-debian-package

00:01:30