Elaborate on usage in README

README.md

@@ -1,7 +1,35 @@
 # silverutil
-A utility to read (and, eventually, modify!) the contents of SilverDB files from iPods.
+A utility to read and modify the contents of SilverDB files within iPod firmware. Tested on 5th, 6th, and 7th generation iPod nanos.
 
-Tested on 5th, 6th, and 7th generation iPod nanos.
+## Usage
+For up-to-date information, run `silverutil -h`:
+```
+Usage: silverutil <COMMAND>
+
+Commands:
+  extract  Extracts sections within database into a YAML representation
+  info     Displays information about contents present within sections
+  create   Creates a database from a YAML representation
+  help     Print this message or the help of the given subcommand(s)
+
+Options:
+  -h, --help     Print help
+  -V, --version  Print version
+```
+
+Each section is transformed to a separate YAML file. An example of a such a representation is as follows, from the section `StrT` (named `StrT.yaml`):
+```yaml
+magic: StrT
+is_sequential: 1
+resources:
+- id: 1
+  contents: !String orientation.landscape
+- id: 2
+  contents: !String orientation.alt
+# [... continues ...]
+```
+
+The special file `metadata.yaml` is used to preserve the order of sections.
 
 ## Format
 Within the external `rsrc` ("iPod Resources") filesystem, UI translations and date/time locale can be found in `SilverDB.xx_XX.LE.bin`), along with bitmap images in `SilverImagesDB.LE.bin`.

src/cli/src/main.rs

@@ -10,7 +10,7 @@ mod marshal;
 #[command(author, version, about, long_about = None)]
 struct Cli {
     #[command(subcommand)]
-    command: Option<Subcommands>,
+    command: Subcommands,
 }
 
 #[derive(Subcommand)]
@@ -35,10 +35,7 @@ enum Subcommands {
 
 fn main() {
     let cli = Cli::parse();
-    // We should not have optional subcommands.
-    let subcommand = cli.command.unwrap();
-
-    match subcommand {
+    match cli.command {
         Subcommands::Extract {
             database_path,
             output_dir,