Add option to show help pane on the right side

> e1ven
>
> It provides help, but since it's the bottom half of the window, it's often scrolling off the screen, and can't be easily read. Perhaps putting on the right 50% of the screen would help? For instance, try ec2 describe-instances --filters .. Most of the filter syntax isn't displayed.

[Reddit Source](https://www.reddit.com/r/sysadmin/comments/3x2wns/awsshell_the_official_supercharged_aws_cli/cy14fyu)

No file or test is named in the issue. Reproduce the layout with `ec2 describe-instances --filters ..`, then locate the help-pane entry point and its window layout; the change is complete when help appears on the right side and filter syntax remains readable without scrolling off-screen.

Written by the indexing model from the issue text.