client: show defaults when config help screen is displayed

[alessio]

Closes: #5895
Thanks: @njmurarka for pointing this out.

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For contributor use:

• 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.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer

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For admin use:

• Added appropriate labels to PR (ex. WIP, R4R, docs, etc)
• Reviewers assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #5896 into master will increase coverage by 0.04%.
The diff coverage is 86.66%.

@@            Coverage Diff             @@
##           master    #5896      +/-   ##
==========================================
+ Coverage   56.80%   56.84%   +0.04%     
==========================================
  Files         342      342              
  Lines       20046    20060      +14     
==========================================
+ Hits        11388    11404      +16     
+ Misses       7808     7806       -2     
  Partials      850      850              

[tac0turtle]

LGTM