don't generate HTML preview in nightly-readme-build.yml #79

Job	Run time
R Package Checks / docs-check / docs-check	1m 40s
R Package Checks / codecov / test-coverage	1m 30s
R Package Checks / check-R-updates / updated-files	7s
R Package Checks / r-cmd-check / macOS-latest (release)	1m 31s
R Package Checks / r-cmd-check / windows-latest (release)	2m 57s
R Package Checks / lintr / lint	1m 26s
R Package Checks / r-cmd-check / windows-latest (3.6)	4m 42s
R Package Checks / r-cmd-check / windows-latest (4.1)	5m 36s
R Package Checks / r-cmd-check / ubuntu-latest (release)	1m 54s
R Package Checks / r-cmd-check / ubuntu-latest (devel)	2m 56s
R Package Checks / r-cmd-check / ubuntu-latest (oldrel-1)	1m 34s
R Package Checks / r-cmd-check / ubuntu-latest (oldrel-2)	1m 46s
R Package Checks / r-cmd-check / ubuntu-latest (oldrel-3)	1m 39s
R Package Checks / r-cmd-check / ubuntu-latest (oldrel-4)	1m 38s
R Package Checks / version-check	0s
	30m 56s

Provide feedback