docs: Make clap_derive reflect it not being user-facing

clap_derive/README.md

@@ -1,147 +1,6 @@
 # clap_derive
 
-Parse command line argument by defining a struct.  It combines [structopt](https://github.com/TeXitoi/structopt) and [clap](https://crates.io/crates/clap) into a single experience. This crate is used by clap, and not meant to be used directly by
-consumers.
-
-## Documentation
-
-Find it on [Docs.rs](https://docs.rs/clap_derive).  You can also check the [examples](https://github.com/clap-rs/clap/tree/master/clap_derive/examples) and the [changelog](https://github.com/clap-rs/clap/blob/master/CHANGELOG.md).
-
-## Example
-
-Add `clap` to your dependencies of your `Cargo.toml`:
-
-```toml
-[dependencies]
-clap = "3"
-```
-
-And then, in your rust file:
-```rust,no_run
-use std::path::PathBuf;
-use clap::{Parser, ValueHint};
-
-/// A basic example
-#[derive(Parser, Debug)]
-#[clap(name = "basic")]
-struct Opt {
-    // A flag, true if used in the command line. Note doc comment will
-    // be used for the help message of the flag. The name of the
-    // argument will be, by default, based on the name of the field.
-    /// Activate debug mode
-    #[clap(short, long)]
-    debug: bool,
-
-    // The number of occurrences of the `v/verbose` flag
-    /// Verbose mode (-v, -vv, -vvv, etc.)
-    #[clap(short, long, parse(from_occurrences))]
-    verbose: u8,
-
-    /// Set speed
-    #[clap(short, long, default_value = "42")]
-    speed: f64,
-
-    /// Output file
-    #[clap(short, long, parse(from_os_str), value_hint = ValueHint::FilePath)]
-    output: PathBuf,
-
-    // the long option will be translated by default to kebab case,
-    // i.e. `--nb-cars`.
-    /// Number of cars
-    #[clap(short = 'c', long)]
-    nb_cars: Option<i32>,
-
-    /// admin_level to consider
-    #[clap(short, long)]
-    level: Vec<String>,
-
-    /// Files to process
-    #[clap(name = "FILE", parse(from_os_str), value_hint = ValueHint::AnyPath)]
-    files: Vec<PathBuf>,
-}
-
-fn main() {
-    let opt = Opt::parse();
-    println!("{:#?}", opt);
-}
-```
-
-Using this example:
-```bash
-$ ./basic
-error: The following required arguments were not provided:
-    --output <output>
-
-USAGE:
-    basic --output <output> --speed <speed>
-
-For more information try --help
-$ ./basic --help
-basic 0.3.0
-Guillaume Pinot <texitoi@texitoi.eu>, others
-A basic example
-
-USAGE:
-    basic [OPTIONS] --output <output> [--] [file]...
-
-ARGS:
-    <FILE>...    Files to process
-
-OPTIONS:
-    -c, --nb-cars <nb-cars>    Number of cars
-    -d, --debug                Activate debug mode
-    -h, --help                 Print help information
-    -l, --level <level>...     admin_level to consider
-    -o, --output <output>      Output file
-    -s, --speed <speed>        Set speed [default: 42]
-    -V, --version              Print version information
-    -v, --verbose              Verbose mode (-v, -vv, -vvv, etc.)
-
-ARGS:
-    <file>...    Files to process
-$ ./basic -o foo.txt
-Opt {
-    debug: false,
-    verbose: 0,
-    speed: 42.0,
-    output: "foo.txt",
-    nb_cars: None,
-    level: [],
-    files: [],
-}
-$ ./basic -o foo.txt -dvvvs 1337 -l alice -l bob --nb-cars 4 bar.txt baz.txt
-Opt {
-    debug: true,
-    verbose: 3,
-    speed: 1337.0,
-    output: "foo.txt",
-    nb_cars: Some(
-        4,
-    ),
-    level: [
-        "alice",
-        "bob",
-    ],
-    files: [
-        "bar.txt",
-        "baz.txt",
-    ],
-}
-```
-
-## clap_derive rustc version policy
-
-- Minimum rustc version modification must be specified in the [changelog](https://github.com/clap-rs/clap_derive/blob/master/CHANGELOG.md) and in the [travis configuration](https://github.com/clap-rs/clap_derive/blob/master/.travis.yaml).
-- Contributors can increment minimum rustc version without any justification if the new version is required by the latest version of one of clap_derive's dependencies (`cargo update` will not fail on clap_derive).
-- Contributors can increment minimum rustc version if the library user experience is improved.
-
-## Why
-
-I've (@TeXitoi) used [docopt](https://crates.io/crates/docopt) for a long time (pre rust 1.0). I really like the fact that you have a structure with the parsed argument: no need to convert `String` to `f64`, no useless `unwrap`. But on the other hand, I don't like to write by hand the usage string. That's like going back to the golden age of WYSIWYG editors.  Field naming is also a bit artificial.
-
-Today, the new standard to read command line arguments in Rust is [clap](https://crates.io/crates/clap).  This library is so feature full! But I think there is one downside: even if you can validate argument and expressing that an argument is required, you still need to transform something looking like a hashmap of string vectors to something useful for your application.
-
-Now, there is stable custom derive. Thus I can add to clap the automatic conversion that I miss. Here is the result.
+Macro implementation for clap's derives.
 
 ## License