Constant ZSH_HELP

Source
const ZSH_HELP: &str = r#"
# To enable `cargo xtask` completions, there are two steps:
#
# 1. Use `rustup completions cargo` to set up `cargo` completions.
# 2. Copy this script into your `.zshrc`
#
# NOTE: This is _not_ your typical `zsh` completion!
#
# No need to `compdef` anything. Just make sure that the `_cargo-xtask` function
# is in-scope, and that `rustup completions cargo` infrastructure redirect
# `cargo xtask` completions to that function.
"#;