A few small tweaks to the new `explore` command:
1. Rewrote the help text a bit.
1. I think it's important to mention `:try` up front.
2. Removed the info about `:help foo` because it's currently supported
by very few subcommands
2. Make `exit_esc` default to true. I want to avoid people getting stuck
in `explore` like they get stuck in Vim
3. ~~Always show the help message ("For help type :help") on startup~~
1. The message is small+unobtrusive and I don't this is worth a
configuration item
4. Exit the information view when Escape is pressed
5. General typo+grammar cleanup
cc: @zhiburt @fdncred
