Add note about MSRV compile failure. #1

Job	Run time
cargo clippy (android) (armv7-linux-androideabi)	45s
cargo clippy (windows-latest)	1m 26s
cargo clippy (android) (aarch64-linux-android)	45s
cargo check (msrv) (android) (armv7-linux-androideabi)	19s
cargo clippy (macos-14)	42s
cargo check (msrv) (windows-latest)	27s
cargo clippy (android) (x86_64-linux-android)	46s
cargo check (msrv) (macos-14)	32s
cargo clippy (ubuntu-latest)	44s
cargo check (msrv) (android) (aarch64-linux-android)	16s
cargo check (msrv) (ubuntu-latest)	15s
cargo check (msrv) (android) (x86_64-linux-android)	20s
cargo doc (windows-latest)	1m 2s
cargo fmt	24s
cargo doc (macos-14)	32s
cargo test (windows-latest)	1m 11s
cargo doc (ubuntu-latest)	28s
cargo test (macos-14)	38s
cargo test (ubuntu-latest)	38s
	12m 10s

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