Fix StructOpt's about

The problem is described in these issues:
TeXitoi/structopt#333
TeXitoi/structopt#391

The is easiest workaround is to remove doc comments from `Options` and
`Subcommand`

src/cli/mod.rs

@@ -20,9 +20,8 @@ lazy_static! {
     pub static ref SUBCOMMAND: &'static Subcommand = &CLI.subcommand;
 }
 
-// This doc comment is for StructOpt
-/// Dotfiles installation manager
 #[derive(Debug, StructOpt)]
+#[structopt(about = "Dotfiles installation manager")]
 pub struct Cli {
     #[structopt(flatten)]
     options: Options,
@@ -31,7 +30,6 @@ pub struct Cli {
     subcommand: Subcommand,
 }
 
-/// CLI Options
 #[derive(Debug, StructOpt)]
 pub struct Options {
     /// Set a custom dotfiles directory

src/cli/subcommand/mod.rs

@@ -13,11 +13,6 @@ use completion::Completion;
 use exec::Exec;
 use install::Install;
 
-/// All the subcommand supported by the application
-///
-/// They should be used with structopt's [`subcommand`] attribute
-///
-/// [`subcommand`]: https://docs.rs/structopt/#subcommands
 #[derive(Debug, StructOpt)]
 pub enum Subcommand {
     Install(Install),