Update diagram to mermaid or latex.

The diagram of higher-level workflow design is now in png format.
But since it needs some memos and annotations, regarding the status of some of software, we'd better keep them more editable.

The IDS owner also said the mermaid is fine but I had trouble make it work in the documentation build framework...
There is a latex code for this diagram so we can probably use latex instead.

Latex Version

Mermaid Version

stateDiagram
    direction TB
    Step0: Starting Experiment
    Step1: Setting up Measurement Strategy
    Step0 --> Step1
    state ECDC {
        Step2: Data Readout from Detectors
    }
    Step1 --> ECDC
    state SCIPP {
        Step3.0: TOA to TOF
    }
    ECDC --> SCIPP
    state DIALS {
        direction LR
        Step3.1: 1. Spot Finding
        Step3.2: 2. TOF to &lambda
        Step3.3: 3. Indexing
        Step3.4: 4. Refine Indexing
        Step3.5: 5. Spot Integration
        Step3.1 --> Step3.2
        Step3.2 --> Step3.3
        Step3.3 --> Step3.4
        Step3.4 --> Step3.5
    }
    SCIPP --> DIALS
    state pyscale: pyscale {
        Step3.6: Scaling (temporarily using LSCALE)
    }
    DIALS --> pyscale
    state CCP4 {
        direction LR
        Step3.7: Merging, AIMLESS
        Step3.8: I to SFs
        Step3.7 --> Step3.8
    }
    pyscale --> CCP4
    state PHENIX {
        direction LR
        Step4.0: Phasing
        Step4.0 --> Step4.1
        state MODELCOMPLETED {
            state refine <<choice>>
            state map <<choice>>
            Step4.1: Model Completion
            Step4.2: Refinement
            Step4.3: MapCalculation
            Step4.4: Done
            Step4.1 --> Step4.2
            Step4.2 --> refine
            refine --> Step4.4
            refine --> Step4.3
            Step4.3 --> map
            map --> Step4.4
            map --> Step4.1
        }
    }
    CCP4 --> PHENIX
    Step5: Finished Experiment
    PHENIX --> Step5

Additional explanation of the last step.

The last iteration between model-completion, refinement and map calculation is more clear in the mermaid diagram, but the if-node may need more clear annotation.

Locate the current PNG diagram and the documentation build framework, then review the provided Mermaid and LaTeX versions. Choose an editable format that renders in the documentation, preserves the workflow and annotations, and makes the final model-completion loop clear.