Add note about MSRV compile failure. #2

Job	Run time
cargo clippy (windows-latest)	1m 25s
cargo clippy (android) (armv7-linux-androideabi)	46s
cargo clippy (macos-14)	43s
cargo clippy (android) (aarch64-linux-android)	46s
cargo check (msrv) (windows-latest)	1m 11s
cargo clippy (ubuntu-latest)	48s
cargo clippy (android) (x86_64-linux-android)	44s
cargo check (msrv) (android) (armv7-linux-androideabi)	34s
cargo check (msrv) (macos-14)	35s
cargo check (msrv) (android) (aarch64-linux-android)	36s
cargo doc (windows-latest)	1m 7s
cargo check (msrv) (android) (x86_64-linux-android)	39s
cargo fmt	21s
cargo doc (macos-14)	30s
cargo check (msrv) (ubuntu-latest)	33s
cargo doc (ubuntu-latest)	30s
cargo test (windows-latest)	1m 25s
cargo test (macos-14)	35s
cargo test (ubuntu-latest)	39s
	14m 27s

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