* Indicate supported Lua versions

* Add license preamble to valid.lua
* Add reference optimizations for non-JIT'd Lua versions
* Explicitely indicate what is returned from every function
* Add docstrings to all functions in valid.lua

README.md

@@ -5,6 +5,7 @@ A library for Lua to validate various values and table structures.
 ## Table of Contents
 
 - [Features](#features)
+- [Supported Lua Versions](#supported-lua-versions)
 - [Installation](#installation)
 - [Basic Usage](#basic-usage)
   - [Validating Simple Data Types](#validating-simple-data-types)
@@ -32,6 +33,15 @@ A library for Lua to validate various values and table structures.
 - Detailed error reporting with paths to invalid keys or indices.
 - Nested validations for complex table structures.
 
+## Supported Lua Versions
+
+`valid.lua` is tested with:
+
+- Lua 5.1 (including LuaJIT)
+- Lua 5.2
+- Lua 5.3
+- Lua 5.4
+
 ## Installation
 
 Copy the [`valid.lua`](valid.lua) file to a directory in your `LUA_PATH`.