Use Pager for help text option only works on top-level help

[scott-vincent]

Describe the bug
The recent change to stop using the pager when displaying help text only works for top-level help. If I do, e.g. "command subCommand -h" the pager is still used.

To Reproduce
Steps to reproduce the behavior:

1. Using this version of the library '2.3.3'
2. Change was added here: #216
3. With these arguments 'command subCommand -h'
4. Pager is still being used when app.UserPagerForHelpText = false

Expected behavior
The pager should never be used if UsePagerForHelpText is false.

[natemcmaster]

I would accept a PR to fix this. The workaround is to set UsePagerForHelpText=false on subcommands as well.