Update CSP docs

[sajith]

Issue is #137. Changes:

• Consolidate docs and images under docs folder.
• Remove old/unused test data files and references to those files from the doc.
• Formatting changes.

This is not ready yet. I have added some TODO items in the doc. I will need some help/hand-holding there.

[coveralls]

Pull Request Test Coverage Report for Build 10563024958

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 86.016%

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Totals
Change from base Build 10479975493:	0.0%
Covered Lines:	1124
Relevant Lines:	1271

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💛 - Coveralls

[YufengXin]

@sajith I updated the readme, please check and merge into main. It definitely could use more contents, but it's more accurate and updated now. Thanks.

[YufengXin]

needs proofreading and further edits from Sajith

[sajith]

@YufengXin Let us merge this now. It would be useful to have a detailed description of the diagram (what the yellow, green, and blue regions and the numbers mean) and how that relates to code, but that can be a later step.