DOCS: improve ledger docs

[gamarin2]

Closes #3337

• Targeted PR against correct branch (see CONTRIBUTING.md)

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.

• Wrote tests

• Updated relevant documentation (docs/)

• Added entries in PENDING.md with issue #

• rereviewed Files changed in the github PR explorer

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For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #3649 into develop will increase coverage by 0.33%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #3649      +/-   ##
===========================================
+ Coverage    60.92%   61.26%   +0.33%     
===========================================
  Files          188      186       -2     
  Lines        14084    13998      -86     
===========================================
- Hits          8581     8576       -5     
+ Misses        4959     4878      -81     
  Partials       544      544