Deduplicate metadata in clap by using crate macros

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "newdoc"
-version = "2.3.4"
-description = "The newdoc tool generates pre-populated module and assembly files formatted with AsciiDoc, which are used in Red Hat and Fedora documentation. The generated files follow the template guidelines maintained by the Modular Documentation initiative: https://redhat-documentation.github.io/modular-docs/."
+version = "2.3.5"
+description = "Generate pre-populated module files formatted with AsciiDoc that are used in Red Hat and Fedora documentation."
 authors = ["Marek Suchánek <[email protected]>"]
 license = "GPL-3.0-or-later"
 edition = "2018"

src/main.rs

@@ -3,7 +3,7 @@ use std::io::{self, Write};
 use std::path::PathBuf;
 
 extern crate clap;
-use clap::{App, AppSettings, Arg, Values};
+use clap::{App, AppSettings, Arg, crate_authors, crate_description, crate_name, crate_version, Values};
 
 extern crate colored;
 use colored::*;
@@ -69,10 +69,10 @@ struct Options {
 
 fn main() {
     // Define command-line options
-    let cmdline_args = App::new("newdoc")
-        .version("v2.3.4")
-        .author("Marek Suchánek")
-        .about("Generate an AsciiDoc file using a modular template")
+    let cmdline_args = App::new(crate_name!())
+        .version(crate_version!())
+        .author(crate_authors!())
+        .about(crate_description!())
         // If no arguments are provided, print help
         .setting(AppSettings::ArgRequiredElseHelp)
         .arg(