JP-3590: Fix config_asdf doc entry

[drlaw1558]

Resolves JP-3590

Closes #8405

Checklist for maintainers

• added entry in CHANGES.rst within the relevant release section
• updated or added relevant tests
• updated relevant documentation
• added relevant milestone
• added relevant label(s)
• ran regression tests, post a link to the Jenkins job below.
  How to run regression tests on a PR
• Make sure the JIRA ticket is resolved properly

[drlaw1558]

Not sure whether doc fixes need a change log entry or not

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.62%. Comparing base (2fb073e) to head (461da3b).
Report is 18 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8406      +/-   ##
==========================================
+ Coverage   75.31%   75.62%   +0.31%     
==========================================
  Files         474      476       +2     
  Lines       38965    39467     +502     
==========================================
+ Hits        29345    29847     +502     
  Misses       9620     9620              

Flag	Coverage Δ		*Carryforward flag
nightly	77.63% <ø> (+0.30%)	⬆️	Carriedforward from 2fb073e

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