Update documentation

README.md

@@ -2,4 +2,45 @@
 
 Generate i18n JSON/JS files from a Google Sheets spreadsheet
 
-:warning: **WIP: Do NOT use for production**
+## Installation
+
+### npm
+
+`npm install --save-dev google-sheets-i18n-generator`
+
+### yarn
+
+`yarn add --dev google-sheets-i18n-generator`
+
+## Usage
+
+1. Create a Google Sheets spreadsheet to store the i18n strings
+2. Enable the Google Sheets API following [this documentation](https://developers.google.com/sheets/api/quickstart/nodejs#step_1_turn_on_the)
+3. Download the `client_secret.json` and `credentials.js` files to access the Google Sheets API
+3. Copy the ID of the spreadsheet (e.g. in this URL `https://docs.google.com/spreadsheets/d/1kjNb2-Tpn_1Pcd6pid22fBQlr8nd6oa1ltXwKNj1Gz11/edit#gid=0` the ID is `1kjNb2-Tpn_1Pcd6pid22fBQlr8nd6oa1ltXwKNj1Gz11`)
+4. Run the command: `gs-i18n --spreadsheet <id>`
+5. The JSON files are generated in the `./locales` folder
+
+## API
+
+```
+Usage: gs-i18n --spreadsheet <id> [options]
+
+Options:
+  -v, --version           output the version number
+  -c, --client <path>     path of client secret file (defaults to ./client_secret.json)
+  -f, --format <format>   format of generated files (available values are cjs, esm and json, defaults json)
+  -k, --key <index>       index of key column (defaults 0)
+  -l, --lang <index>      index of first language column (defaults 1)
+  -o, --output <path>     path of output directory (defaults to ./locales)
+  -r, --range <range>     range of data to parse (defaults Sheet1)
+  -s, --spreadsheet <id>  id of spreadsheet to parse (required)
+  -t, --token <path>      path of credentials file (defaults to ./credentials.json)
+  -h, --help              output usage information
+```
+
+## TODO
+
+* Improve documentation
+* Create unit tests
+* Improve code

index.js

@@ -19,6 +19,8 @@ const DEFAULT_TOKEN = './credentials.json'
 
 // Generate documentation and parse arguments
 program
+	.name("gs-i18n")
+	.usage('--spreadsheet <id> [options]')
 	.version(module.exports.version, '-v, --version')
 	.option(
 		'-c, --client <path>',