WebHost: allow lists without leading blank line in markdown (#4064) #20467

Job	Run time
Test hosting with 3.12 on ubuntu-latest	3m 11s
Test Python 3.8 ubuntu-latest	4m 35s
Test Python 3.9 ubuntu-latest	4m 23s
Test Python 3.10 ubuntu-latest	4m 23s
Test Python 3.11 ubuntu-latest	4m 7s
Test Python 3.12 ubuntu-latest	5m 53s
Test Python 3.8 windows-latest	6m 34s
Test Python 3.12 windows-latest	8m 16s
Test Python 3.12 macos-latest	3m 13s
	44m 35s

Provide feedback