README incorrectly claims that nightly rust is needed

[rursprung]

the README claims that nightly rust is needed to compile the crate:

statime/README.md

Lines 28 to 30 in 942ccaf

	## Rust version
	Statime requires a nigthly version of cargo/rust. The easiest way to obtain these is through [rustup](https://rustup.rs)

however, this does not seem to be the case as it compiles fine with rust 1.82 (and probably earlier). the only usage of a nightly feature i can see in this repo is TAIT in the statime-stm32
#![feature(type_alias_impl_trait)]

this is also proven by the fact that the CI uses stable rust (only statime-stm32 has a rust-toolchain.toml, so for the others it picks stable):

statime/.github/workflows/rust.yml

Line 33 in 942ccaf

toolchain: stable

thus i think this can either be completely removed from the README or at least reworded to clearly state that it only applies to statime-stm32 (and in that case the typo in the word nigthly should be fixed as well to make Ctrl+F easier 😉)