Specify the correct default values for sudo_flags
Specify the correct default values for sudo_flags

The correct default options for sudo_flags can be found at: https://github.com/ansible/ansible/blob/devel/lib/ansible/constants.py#L181

Slightly alter explanation of '-H' so as not to confuse it with -E, --preserve-env (which preserves existing environment variables).

When adding the two other options, include short explanations of those options.

Add note about '-n', which did not appear in 1.x I believe, and which bit me.
thaim/ansible,thaim/ansible