docs: add in-situ analysis

[BenWibking]

Description

Adds documentation for enabling in-situ analysis of simulations.

Also: updates the documentation on how to read a time series of plotfiles with VisIt.

Related issues

N/A

Checklist

Before this pull request can be reviewed, all of these tasks should be completed. Denote completed tasks with an x inside the square brackets [ ] in the Markdown source below:

• I have added a description (see above).
• I have added a link to any related issues see (see above).
• I have read the Contributing Guide.
• I have added tests for any new physics that this PR adds to the code.
• I have tested this PR on my local computer and all tests pass.
• I have manually triggered the GPU tests with the magic comment /azp run.
• I have requested a reviewer for this PR.

[markkrumholz]

I'll hold off on reviewing this until #581 is finalized and merged, since the exact functionality is still being iterated.

[markkrumholz]

See inline comments.

[BenWibking]

I've re-worded things to avoid "weighting" as you suggested. Let me know if it is sufficiently clear.

[BenWibking]

@markkrumholz Can you re-review?

[markkrumholz]

Two final minor comments: in the example input file for on-the-fly PDFs, the documentation / comments do not currently state the default behavior for the weight-by and min/max options. You should state what these default to, i.e., if you don't specify how to weight, is it weighted by mass, volume, cell count? What are the default choices for min/max if you don't specify?

[BenWibking]

Two final minor comments: in the example input file for on-the-fly PDFs, the documentation / comments do not currently state the default behavior for the weight-by and min/max options. You should state what these default to, i.e., if you don't specify how to weight, is it weighted by mass, volume, cell count? What are the default choices for min/max if you don't specify?

I've added both of these. See inline comments.