Merge branch '1-root-level-description' into 'v0.1.1'

Added App::long_desc(self) which sets the root level description

See merge request arkham/arkham!1

examples/fib.rs

@@ -4,6 +4,7 @@ fn main() {
     let _ = App::new()
         .name("Fibonacci App")
         .version("1.0")
+        .long_desc("This app can be used to calculate fibonacci numbers")
         .command(
             Command::new("fib")
                 .opt(

src/app.rs

@@ -140,6 +140,18 @@ impl App {
         self
     }
 
+    /// Sets the longe description for the bare app. This will be displayed in the help content
+    /// when no additional subcommands are given.
+    /// Example:
+    /// ```rust
+    /// use arkham::{App, Command, Context};
+    /// App::new().long_desc("This app does all the things");
+    /// ```
+    pub fn long_desc(mut self, desc: &str) -> Self {
+        self.root.long_desc = Some(desc.to_string());
+        self
+    }
+
     /// Execute the app and any specified handlers based on the passed arguemnts. This function is
     /// mostly used for testing or any situation where you need to pass arbitrary arguments instead
     /// of using the ones passed to the application.