feat(cli): add descriptions of args/flags

src/cli.rs

@@ -5,11 +5,18 @@ use clap::Parser;
 #[derive(Parser, Debug)]
 #[command(version, about, long_about = None)]
 pub struct Args {
+    /// word to define
     pub word: String,
+
+    /// language of the word
     #[arg(short, long, default_value = "en")]
     pub language: String,
+
+    /// parts of speech to show
     #[arg(short, long, default_values = constants::POSSIBLE_PARTS_OF_SPEECH)]
     pub parts_of_speech: Vec<String>,
+
+    /// show examples for definitions
     #[arg(short, long, action = clap::ArgAction::SetTrue)]
     pub examples: bool,
 }