docs: update volar package name (#4212) #4802

Job	Run time
test (ubuntu-latest, 27.2, false)	2m 52s
test (ubuntu-latest, 28.2, false)	3m 4s
test (ubuntu-latest, 29.1, false)	3m 30s
test (macos-latest, 27.2, false)	5m 29s
test (macos-latest, 28.2, false)	4m 42s
test (macos-latest, 29.1, false)	5m 29s
test (windows-latest, 27.2, false)	12m 5s
test (windows-latest, 28.2, false)	4m 11s
test (windows-latest, 29.1, false)	3m 46s
test (ubuntu-latest, snapshot, true)	2m 37s
test (macos-latest, snapshot, true)	2m 56s
test (windows-latest, snapshot, true)	48s
	51m 29s

Provide feedback