Add notes about cache limitations in the inventory plugin dev guide #8933

Job	Run time
nox / Run nox actionlint session	16s
nox / Run nox static session	18s
nox / Run nox checkers(rstcheck) session	1m 27s
nox / Run nox pip-compile session	34s
nox / Run nox typing session	31s
nox / Run nox formatters_check session	18s
nox / Run nox checkers(docs-build) session	1m 48s
nox / Run nox checkers(rst-yamllint) session	33s
nox / Run nox spelling session	15s
nox / Run nox zizmor session	14s
check	5s
	6m 19s

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