Allow multiple files in generic packages

[KN4CK3R]

This PR allows multiple files in generic packages and updates the docs.

fixes #20651

[codecov-commenter]

Codecov Report

:exclamation: No coverage uploaded for pull request base (main@96440e6). Click here to learn what that means. The diff coverage is 75.00%.

@@           Coverage Diff           @@
##             main   #20661   +/-   ##
=======================================
  Coverage        ?   46.84%           
=======================================
  Files           ?      979           
  Lines           ?   135924           
  Branches        ?        0           
=======================================
  Hits            ?    63672           
  Misses          ?    64429           
  Partials        ?     7823           

Impacted Files	Coverage Δ
routers/api/packages/generic/generic.go	74.00% <66.66%> (ø)
routers/api/packages/api.go	91.16% <100.00%> (ø)

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[lunny]

Why sanitizeParameters was removed?

[KN4CK3R]

It's only needed for the upload endpoint so I moved it there.