Documentation: insist on merging vs concatenating order semantics

[jponge]

Fixes #1275

[codecov]

Codecov Report

Merging #1313 (78e1927) into main (263d101) will increase coverage by 0.20%.
The diff coverage is n/a.

❗ Current head 78e1927 differs from pull request most recent head 5ed6bfb. Consider uploading reports for the commit 5ed6bfb to get more accurate results

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1313      +/-   ##
============================================
+ Coverage     89.61%   89.82%   +0.20%     
- Complexity     3333     3342       +9     
============================================
  Files           458      458              
  Lines         13217    13217              
  Branches       1639     1639              
============================================
+ Hits          11845    11872      +27     
+ Misses          722      697      -25     
+ Partials        650      648       -2     

see 14 files with indirect coverage changes