Change array<int...> to list<...> in PHP doc

[phil-davis]

I found this PR again today (2024-04-18!).
It looks like I did something reasonable, but, TBH, I don't remember what caused me to start doing this sort of minor refactoring of the PHPdoc.

Maybe we did this already in other sabre repos? I would have to search around to find it.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.70%. Comparing base (93732bd) to head (c7c408f).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #103   +/-   ##
=======================================
  Coverage   97.70%   97.70%           
=======================================
  Files           1        1           
  Lines         174      174           
=======================================
  Hits          170      170           
  Misses          4        4           

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[staabm]

in this case it looks harmless and fine.

when changing types in api methods we need to be more careful, because lists have a few more implications then just beeing a array with a int key.