docs: add NPM version label to README

README.md

@@ -1,4 +1,6 @@
 # Error Codes
+[![NPM Version](https://img.shields.io/npm/v/%40pretendonetwork%2Ferror-codes)](https://www.npmjs.com/package/@pretendonetwork/error-codes)
+
 Translated JSON files for known error codes used by the Wii U and 3DS
 
 ## Path Structure
@@ -78,4 +80,4 @@ The main purpose of this repository is to maintain the JSON translation files. H
 
 - `getModuleInfo(sysmodule, locale)` - Returns the module information for the locale, or `null` if not found
 - `getErrorInfo(sysmodule, code, locale)` - Returns the error information (including the module information) for the locale. Returns null if either the module or error code is not found
-- `getAllErrors()` - Returns an array of all error codes for all modules in the form `MODULE-CODE`
+- `getAllErrors()` - Returns an array of all error codes for all modules in the form `MODULE-CODE`