Unclear which flags are used by which roles

[chrishobcroft]

Describe the bug

Currently, it isn't easy to determine which flags (e.g. -maxTicketEV) are used by which role (e.g. -broadcaster or -orchestrator)

To Reproduce

1. Run ./livepeer --help
2. See a number of flags, with descriptions of how to use them e.g.:

  -maxTicketEV string
    	The maximum acceptable expected value for PM tickets (default "3000000000000")

3. Be confused about whether this flag is to be used with -broadcaster role or -orchestrator role.
4. Try running ./livepeer with the -orchestrator flag and also -maxTicketEV
5. Discover that setting the -maxTicketEV in this case is ignored
6. Be confused about why it didn't throw an error saying "you can't use -maxTicketEV with -orchestrator" (or something similar)

Expected behavior

I expect it to be made clear (e.g. in --help) which flags can influence the operations of which role.

Also, if I use a flag with a role where the role ignores the flag, I at least expect to be warned about it :)

[hthillman]

The quick wins here are probably:

• add it to documentation (e.g., here)
• add it to --help

Note that these can happen independently of one another.

Marked as good first issue and help wanted