Minor: Update SIGMOD paper reference url #27768

Job	Run time
cargo check	3m 42s
Check cargo fmt	49s
build with wasm-pack	2m 17s
cargo test (macos)	20m 16s
Verify Vendored Code	44s
cargo test (macos-aarch64)	10m 30s
cargo test (win64)	34m 22s
Verify MSRV (Min Supported Rust Version)	6m 39s
cargo test (amd64)	9m 59s
cargo test datafusion-cli (amd64)	4m 14s
clippy	5m 40s
cargo test hash collisions (amd64)	9m 23s
cargo doc	3m 38s
cargo test doc (amd64)	12m 56s
cargo examples (amd64)	11m 49s
Run sqllogictest with Postgres runner	3m 38s
cargo test pyarrow (amd64)	3m 12s
verify benchmark results (amd64)	10m 53s
check Cargo.toml formatting	3m 0s
check configs.md is up-to-date	3m 23s
	2h 41m 4s

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