doc: 6725 add pcap file logging variable details v3

[jmtaylor90]

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  https://docs.suricata.io/en/latest/devguide/contributing/contribution-process.html
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• I have updated the user guide (in doc/userguide/) to reflect the changes made (if applicable)

Link to redmine ticket:
https://redmine.openinfosecfoundation.org/issues/6725

Describe changes:

• fixed typo and addressed comments in previous PRs
• add pcap file name variables documentation

Provide values to any of the below to override the defaults.

To use a pull request use a branch name like pr/N where N is the
pull request number.

Alternatively, SV_BRANCH may also be a link to an
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SV_REPO=
SV_BRANCH=
SU_REPO=
SU_BRANCH=
LIBHTP_REPO=
LIBHTP_BRANCH=

[jufajardini]

LGTM, many thanks! :)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (244a35d) 73.31% compared to head (7798ed2) 82.33%.

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #10294       +/-   ##
===========================================
+ Coverage   73.31%   82.33%    +9.01%     
===========================================
  Files         895      978       +83     
  Lines      148215   272029   +123814     
===========================================
+ Hits       108666   223975   +115309     
- Misses      39549    48054     +8505     

Flag	Coverage Δ
fuzzcorpus	63.52% <ø> (+0.03%)	⬆️
suricata-verify	61.49% <ø> (-0.04%)	⬇️
unittests	62.84% <ø> (?)

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[victorjulien]

Merged in #10413, thanks!