chore(docs): add help command and fix CLI usage examples (#1016)

* feat: add help command and fix CLI usage examples

- Add --help flag and help text to swipl-generate CLI
- Update README to use correct npx swipl-generate command syntax

* feat: update help text to mention only TypeScript generation

Changes CLI help text to specify TypeScript output only, removing
JavaScript option from usage examples and argument descriptions.

---------

Co-authored-by: Jesse Wright <63333554+jeswr@users.noreply.github.com>

Author: justjoheinz

README.md

@@ -100,7 +100,7 @@ the `.js` file instead.
 
 ## Generating an image
 
-Often you will want to bundle a pre-built image of your Prolog file. The easiest way to do this is using the `swipl-generate` command to generate the image. For example in `./examples/generation` the script: `swipl-generate ./max.pl ./dist/max.ts` will generate a file `./dist/max.ts` which contains the image of `./max.pl`. This file can then be imported into your project and used as follows:
+Often you will want to bundle a pre-built image of your Prolog file. The easiest way to do this is using the `swipl-generate` command to generate the image. For example in `./examples/generation` the script: `npx swipl-generate ./max.pl ./dist/max.ts` will generate a file `./dist/max.ts` which contains the image of `./max.pl`. This file can then be imported into your project and used as follows:
 
 ```ts
 import SWIPL from './max';

dist/bin/index.js

@@ -3,6 +3,18 @@
 const { generateLoadedImageFile, generateImageFile } = require('../generateImage')
 const path = require('path');
 
+function showHelp() {
+  console.log(`Usage: swipl-generate <input.pl> <output.ts> [--image-only]
+
+Arguments:
+  input.pl     Prolog source file or HTTP(S) URL
+  output.ts    Output TypeScript file
+
+Options:
+  --image-only Generate image data only
+  --help       Show this help`);
+}
+
 function getPath(pth) {
   return pth.startsWith('http://') || pth.startsWith('https://')
     ? pth
@@ -12,6 +24,12 @@ function getPath(pth) {
 async function mainFunc() {
   let args = process.argv.slice(2);
 
+  // Check for help flag or no arguments
+  if (args.includes('--help') || args.includes('-h') || args.length === 0) {
+    showHelp();
+    return;
+  }
+
   const fn = process.argv.includes('--image-only') ? generateImageFile : generateLoadedImageFile;
   args = args.filter(elem => elem !== '--image-only');