[documentation] Add an example with BlockArrays.jl #1246

Job	Run time
setup_matrix	1m 54s
break (PartiallySeparableNLPModels, latest)	11m 4s
break (PartiallySeparableNLPModels, stable)	8m 15s
break (Percival, latest)	7m 18s
break (Percival, stable)	6m 48s
break (CaNNOLeS, latest)	6m 33s
break (CaNNOLeS, stable)	6m 8s
break (PartitionedVectors, latest)	1m 9s
break (PartitionedVectors, stable)	1m 9s
break (DCISolver, latest)	5m 33s
break (DCISolver, stable)	5m 34s
break (JSOSolvers, latest)	11m 18s
break (JSOSolvers, stable)	11m 16s
break (PartiallySeparableSolvers, latest)	3m 39s
break (PartiallySeparableSolvers, stable)	3m 43s
break (RipQP, latest)	13m 57s
break (RipQP, stable)	14m 16s
break (AdaptiveRegularization, latest)	14m 36s
break (AdaptiveRegularization, stable)	14m 17s
break (FletcherPenaltySolver, latest)	28m 33s
break (FletcherPenaltySolver, stable)	28m 10s
upload	4s
	3h 25m 14s

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