Update docker.adoc

[sjjh]

elaborate that the dir of the docker compose file is arbitrary.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #3181      +/-   ##
=============================================
+ Coverage      58.77%   58.86%   +0.09%     
  Complexity       173      173              
=============================================
  Files           2619     2619              
  Lines         113026   113026              
  Branches        8317     8317              
=============================================
+ Hits           66424    66524     +100     
+ Misses         44118    44007     -111     
- Partials        2484     2495      +11     

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