detect-flowbits: add details for flowbits v6

[hadiqaalamdar]

Task #6309

• I have read the contributing guide lines at https://docs.suricata.io/en/latest/devguide/codebase/contributing/contribution-process.html
• I have signed the Open Information Security Foundation contribution agreement at https://suricata.io/about/contribution-agreement/
• 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/6309
Previous PR: #9971

Describe changes:

• added the recommended changes from the last PR.

SV_BRANCH=OISF/suricata-verify#1526

[codecov]

Codecov Report

Merging #10006 (163e4ce) into master (2fe2d82) will increase coverage by 0.06%.
Report is 161 commits behind head on master.
The diff coverage is 51.42%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #10006      +/-   ##
==========================================
+ Coverage   82.39%   82.46%   +0.06%     
==========================================
  Files         968      970       +2     
  Lines      274337   271390    -2947     
==========================================
- Hits       226047   223791    -2256     
+ Misses      48290    47599     -691     

Flag	Coverage Δ
fuzzcorpus	64.55% <0.00%> (-0.14%)	⬇️
suricata-verify	61.30% <51.42%> (+0.38%)	⬆️
unittests	62.87% <0.00%> (+<0.01%)	⬆️

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[hadiqaalamdar]

accidentally made two commits on this PR. Will be creating a new one shortly.