cli: transform --init as a flag

It makes the --help usage more readable

README.md

@@ -43,13 +43,14 @@ quite difficult.
 
 ```
 treefmt 0.1.0
-The various kinds of commands that `treefmt` can execute
+✨  format all your language!
 
 USAGE:
-    treefmt [FLAGS] [OPTIONS] [SUBCOMMAND]
+    treefmt [FLAGS] [OPTIONS] [paths]...
 
 FLAGS:
     -h, --help       Prints help information
+        --init       Create a new treefmt.toml
     -q, --quiet      No output printed to stdout
     -V, --version    Prints version information
     -v, --verbose    Log verbosity is based off the number of v used
@@ -60,9 +61,8 @@ OPTIONS:
     -C <work-dir>                  Run as if treefmt was started in <work-dir> instead of the current working directory
                                    [default: .]
 
-SUBCOMMANDS:
-    --init    Init a new project with a default config
-    help      Prints this message or the help of the given subcommand(s)
+ARGS:
+    <paths>...    Paths to format [default: .]
 ```
 
 ## Configuration format

src/command/mod.rs

@@ -22,9 +22,9 @@ pub enum Command {
 /// ✨  format all your language!
 #[derive(Debug, StructOpt)]
 pub struct Cli {
-    /// Main command to run
-    #[structopt(subcommand)]
-    pub cmd: Option<Command>,
+    /// Create a new treefmt.toml
+    #[structopt(long = "init")]
+    pub init: bool,
 
     /// Log verbosity is based off the number of v used
     #[structopt(long = "verbose", short = "v", parse(from_occurrences))]
@@ -60,9 +60,10 @@ pub fn cli_from_args() -> anyhow::Result<Cli> {
 
 /// Run a command with the given logger
 pub fn run_cli(cli: &Cli) -> anyhow::Result<()> {
-    match cli.cmd {
-        Some(Command::Init {}) => init_cmd(&cli.work_dir)?,
-        None => format_cmd(&cli.work_dir, &cli.paths)?,
+    if cli.init {
+        init_cmd(&cli.work_dir)?
+    } else {
+        format_cmd(&cli.work_dir, &cli.paths)?
     }
 
     Ok(())