Added examples to the modals documentation #1110

Job	Run time
Clippy	50s
Test (MSRV)	1m 20s
Build docs	1m 26s
Test (stable)	2m 26s
Rustfmt	7s
Test (beta)	2m 6s
Test (nightly)	1m 53s
Test (macOS)	1m 28s
Test (Windows)	5m 13s
Test (no features)	1m 10s
Test (all features - simdjson, cargo test --all-features --lib --tests --examples)	1m 11s
Test (native TLS, cargo test --all-features --features serenity/native_tls_backend --lib --tests ...	1m 24s
	20m 34s

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