Docs: Add note about version counter in `ModelCheckpoint` #25945

Job	Run time
build-packages / init	3s
build-packages / build-packages (lightning)	19s
build-packages / build-packages (fabric)	19s
build-packages / build-packages (pytorch)	20s
install-pkg (ubuntu-22.04, fabric, 3.9)	1m 34s
install-pkg (ubuntu-22.04, fabric, 3.11)	1m 35s
install-pkg (ubuntu-22.04, pytorch, 3.9)	1m 39s
install-pkg (ubuntu-22.04, pytorch, 3.11)	1m 41s
install-pkg (ubuntu-22.04, lightning, 3.9)	1m 39s
install-pkg (ubuntu-22.04, lightning, 3.11)	1m 39s
install-pkg (ubuntu-22.04, notset, 3.9)	1m 37s
install-pkg (ubuntu-22.04, notset, 3.11)	1m 39s
install-pkg (macOS-12, fabric, 3.9)	1m 12s
install-pkg (macOS-12, fabric, 3.11)	1m 3s
install-pkg (macOS-12, pytorch, 3.9)	1m 17s
install-pkg (macOS-12, pytorch, 3.11)	1m 3s
install-pkg (macOS-12, lightning, 3.9)	1m 10s
install-pkg (macOS-12, lightning, 3.11)	1m 3s
install-pkg (macOS-12, notset, 3.9)	1m 18s
install-pkg (macOS-12, notset, 3.11)	1m 5s
install-pkg (windows-2022, fabric, 3.9)	2m 0s
install-pkg (windows-2022, fabric, 3.11)	2m 5s
install-pkg (windows-2022, pytorch, 3.9)	2m 25s
install-pkg (windows-2022, pytorch, 3.11)	2m 28s
install-pkg (windows-2022, lightning, 3.9)	2m 22s
install-pkg (windows-2022, lightning, 3.11)	2m 19s
install-pkg (windows-2022, notset, 3.9)	2m 42s
install-pkg (windows-2022, notset, 3.11)	2m 19s
	41m 55s

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