Add credentials collectors explanation pages

[shreyamalviya]

What does this PR do?

Fixes #4212

PR Checklist

• Have you added an explanation of what your changes do and why you'd like to include them?
• Is the TravisCI build passing?
• Was the CHANGELOG.md updated to reflect the changes?
• Was the documentation framework updated to reflect the changes?
• Have you checked that you haven't introduced any duplicate code?

Testing Checklist

• Added relevant unit tests?
• Do all unit tests pass?
• Do all end-to-end tests pass?
• Any other testing performed?

  Tested by {Running the Monkey locally with relevant config/running Island/...}

• If applicable, add screenshots or log transcripts of the feature working

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.07%. Comparing base (dd956f4) to head (85099ce).
Report is 1 commits behind head on develop.

Additional details and impacted files

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  Coverage    77.07%   77.07%           
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  Files          442      442           
  Lines        14135    14135           
  Branches        18       18           
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  Hits         10895    10895           
  Misses        3240     3240           

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[mssalvatore]

I think all of these pages need more information. What is mimikatz? Why would we steal credentials from chrome? How likely are those credentials to be useful in propagation? What's the risk if and SSH key is stolen?

[mssalvatore]

This looks fantastic!

[mssalvatore]

I expanded the explanation of Credentials Collectors:

I have two seemingly conflicting goals for this:

1. Provide context. More specifically, answer the question, "why steal credentials?" To that end, we also need to answer, "how are stolen credentials used?"
2. Keep this page concise and focused.

There may be a little bit too much detail about exploiters here, but I think it's important for users to understand how the stolen credentials are used. I think the solution would be to provide this information under Self-propagating Agent (Issue #4215) and just say, "for information about how stolen credentials are used ... blah blah ... see Self-propagating Agent". Since that page isn't ready yet, I think we should leave this text here. I've left a note in #4215 to extract/repurpose this text as part of that issue.

Similarly, instead of explaining exploiters, I'd rather just use the term "Exploiter" and link to the relevant documentation, but the relevant documentation doesn't exist yet. I've also left a note in #4213.

[shreyamalviya]

I'm still unsure if we should go into this much detail. I suggest we have a separate page explaining the different phases of execution which we could link to wherever required (probably each plugin type's explanation?). This isn't something that's specific to credentials collectors so it doesn't feel right to me here.

[mssalvatore]

I agree that it should be on separate pages, which is why I left notes in #4213 and #4215 to extract it. However, this is information users need to understand. It needs to be somewhere, and if we get interrupted in between now and when we complete #4213 and #4215, at least it's here.