macros: fix references to `Error` in docstrings #310

Job	Run time
Test Suite (stable)	43s
Test Suite (stable, --no-default-features)	35s
Test Suite (stable, --features track-caller)	35s
Clippy (stable)	26s
Check (stable)	17s
Test Suite (stable, --features pyo3)	37s
Rustfmt (stable)	14s
Test Suite (stable, --features auto-install)	37s
Miri	1m 8s
Test Suite	4m 13s
Test Suite (stable, --all-features)	36s
Test Suite (ubuntu-latest)	35s
Test Suite (--no-default-features)	4m 17s
Test Suite (windows-latest)	1m 36s
Test Suite (--features track-caller)	4m 19s
Test Suite (macOS-latest)	1m 20s
Test Suite (--features auto-install)	4m 18s
Test Suite (beta)	35s
Test Suite (beta, --no-default-features)	38s
Test Suite (beta, --features track-caller)	33s
Test Suite (beta, --features pyo3)	36s
Test Suite (beta, --features auto-install)	34s
Test Suite (beta, --all-features)	36s
Test Suite (nightly)	47s
Test Suite (nightly, --no-default-features)	47s
Test Suite (nightly, --features track-caller)	46s
Test Suite (nightly, --features pyo3)	46s
Test Suite (nightly, --features auto-install)	46s
Test Suite (nightly, --all-features)	49s
	34m 39s

Provide feedback