Add documentation to readme

README.md

@@ -1,3 +1,49 @@
 # GitHub Action Document Writer
 
-Creates a README for GitHub actions from an `action.yml` file.
+Provides an opinionated command line application to generated READMEs for
+[GitHub Actions] and [GitHub Workflows].
+
+## Usage
+
+### Documenting GitHub Actions
+
+```
+$ github-action-doc action -h
+Generate documentation for a Github action
+
+USAGE:
+    github-action-doc action <ACTION_FILE>
+
+ARGS:
+    <ACTION_FILE>
+
+OPTIONS:
+    -h, --help    Print help information
+
+```
+
+### Documenting GitHub Workflows
+
+```
+$ github-action-doc workflow -h
+Generate documentation for a Github workflow
+
+USAGE:
+    github-action-doc workflow <WORKFLOW_FILE>
+
+ARGS:
+    <WORKFLOW_FILE>
+
+OPTIONS:
+    -h, --help    Print help information
+```
+
+## Examples
+
+### Actions
+
+* [`actions/checkout@v3`](https://gist.github.com/foo4u/3935d6d9b41fe92b19077515c7a035e5#file-checkout_readme-md)
+* [`actions/setup-java@v3`](https://gist.github.com/foo4u/3935d6d9b41fe92b19077515c7a035e5#file-setup_java_jdk_readme-md)
+
+[GitHub Actions]: https://docs.github.com/en/actions/learn-github-actions/essential-features-of-github-actions
+[GitHub Workflows]: https://github.com/features/actions

src/cli.rs

@@ -2,7 +2,7 @@ use clap::{Subcommand};
 use clap::Parser;
 
 #[derive(Debug, Parser)]
-#[clap(name = "github_action_doc")]
+#[clap(name = "github-action-doc")]
 #[clap(about = "A GitHub action & workflow readme writer", long_about = None)]
 pub struct Cli {
     #[clap(subcommand)]
@@ -17,6 +17,8 @@ pub enum Commands {
         #[clap(required = true, value_parser)]
         action_file: String
     },
+    #[clap(arg_required_else_help = true)]
+    #[clap(about = "Generate documentation for a Github workflow", long_about = None)]
     Workflow {
         #[clap(required = true, value_parser)]
         workflow_file: String