Fixed LazySets docs error #423

Job	Run time
Documentation	6m 37s
Julia 1.6 - ubuntu-latest - x64 - push	8m 51s
Julia 1.6 - ubuntu-latest - x86 - push	10m 28s
Julia 1.6 - macOS-latest - x64 - push	9m 54s
Julia 1.6 - windows-latest - x64 - push	20m 47s
Julia 1.6 - windows-latest - x86 - push	20m 53s
Julia 1 - ubuntu-latest - x64 - push	13m 11s
Julia 1 - ubuntu-latest - x86 - push	7m 0s
Julia 1 - macOS-latest - x64 - push	14m 35s
Julia 1 - windows-latest - x64 - push	14m 25s
Julia 1 - windows-latest - x86 - push	8m 26s
Julia nightly - ubuntu-latest - x64 - push	5m 39s
Julia nightly - ubuntu-latest - x86 - push	7m 40s
Julia nightly - macOS-latest - x64 - push	8m 36s
Julia nightly - windows-latest - x64 - push	7m 20s
Julia nightly - windows-latest - x86 - push	8m 53s
	2h 53m 15s

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