Update documentation regarding `LegendHDF5IO` #1236

Job	Run time
Documentation	15m 21s
Julia 1.10 - ubuntu-latest - x64 - pull_request	27m 36s
Julia 1 - ubuntu-latest - x64 - pull_request	1h 12m 29s
Julia pre - ubuntu-latest - x64 - pull_request	57m 21s
Julia 1 - ubuntu-latest - x86 - pull_request	1h 12m 6s
Julia 1 - macOS-latest - x64 - pull_request	1h 1m 16s
Julia 1 - windows-latest - x64 - pull_request	1h 4m 13s
	6h 10m 22s

Provide feedback