Corrections and enhancements to DirectILL* algorithms' documentation.

...ins/algorithms/WorkflowAlgorithms/DirectILLCollectData.py

...gorithms/WorkflowAlgorithms/DirectILLIntegrateVanadium.py

docs/source/algorithms/DirectILLCollectData-v1.rst

docs/source/algorithms/DirectILLDiagnostics-v1.rst

docs/source/algorithms/DirectILLReduction-v1.rst

docs/source/diagrams/DirectILLCollectData-v1_wkflw.dot

docs/source/techniques/DirectILL.rst