docs: add warning about v2 #276

Job	Run time
Test with standalone (ubuntu-latest, true)	17s
Test with run_install (null, ubuntu-latest)	10s
Test with standalone (ubuntu-latest, false)	13s
Test with dest (4.11.1, ubuntu-latest)	9s
Test with run_install (empty object, ubuntu-latest)	17s
Test with default inputs (4.11.1, ubuntu-latest)	9s
Test with standalone (macos-latest, true)	11s
Test with dest (4.11.1, macos-latest)	13s
Test with run_install (recursive, ubuntu-latest)	12s
Test with default inputs (4.11.1, macos-latest)	12s
Test with standalone (macos-latest, false)	9s
Test with dest (4.11.1, windows-latest)	50s
Test with run_install (global, ubuntu-latest)	14s
Test with default inputs (4.11.1, windows-latest)	37s
Test with standalone (windows-latest, true)	43s
Test with run_install (array, ubuntu-latest)	16s
Test with standalone (windows-latest, false)	29s
Test with run_install (null, macos-latest)	14s
Test with run_install (empty object, macos-latest)	14s
Test with run_install (recursive, macos-latest)	17s
Test with run_install (global, macos-latest)	16s
Test with run_install (array, macos-latest)	16s
Test with run_install (null, windows-latest)	43s
Test with run_install (empty object, windows-latest)	40s
Test with run_install (recursive, windows-latest)	54s
Test with run_install (global, windows-latest)	58s
Test with run_install (array, windows-latest)	1m 3s
	10m 56s

Provide feedback