doc: add usage and api section

README.md

@@ -1,8 +1,80 @@
 # lune-dotenv
-A simple dotenv parser for Lune 
+A dotenv parser for Lune
 
-# TODO
-- [ ] Basic values
+lune-dotenv loads environtment variables from a `.env` file and adds them into `process.env`.
+> [!WARNING]
+> lune-dotenv is still in-development. Some features aren't implemented yet and there might be breaking changes to the API in the future.
+
+* [Installtation](#installation)
+* [Usage](#usage)
+* [API](#api)
+* [TODO](#todo)
+
+
+## Installation
+### Wally
+Coming soon.
+
+### Git submodules
+```
+git submodule add  https://github.com/Eggflaw/lune-dotenv.git
+```
+## Usage
+Create a `.env` file into the root directory of your project.
+```env
+OPENCLOUD_KEY=OPENCLOUDKEYHERE
+SECRETS="SECRETS"
+```
+You can now load the `.env` file with lune-dotenv
+```lua
+local process = require("@lune/process")
+local dotenv = require("Packages/lune-dotenv") -- Assuming you added lune-dotenv into Packages/
+
+dotenv:load() -- Must come before accessing process.env
+print(process.env.OPENCLOUD_KEY) -- Remove after you confirmed it's working
+
+```
+## API
+### `dotenv:load(overwrite: boolean?, path: string?)`
+Loads a `.env` file and add it into `process.env`
+
+By default, `load` will find a `.env` file in the current working directory
+
+If there is an environment variable with the same key name,  lune-dotenv will not overwrite it.
+<br>
+Set `overwrite` to true to avoid this.
+
+```lua
+
+dotenv:load(false)
+print(process.env.HOME) -- "/home/yourname"
+
+--============--
+
+dotenv:load(true)
+print(process.env.HOME) -- "NEWHOME"
+
+```
+
+You can give `load` a custom path instead of finding a `.env` in the current directory
+```lua
+dotenv:load(false, "tests/envs/path.env")
+print(process.env.CUSTOM_PATH)
+```
+
+### `dotenv:parse(str: string): { [string?]: string? }`
+Parse `.env` content and convert it into a table. <br>
+Use this if you don't want to load `.env` into `process.env`
+
+```lua
+local content = fs.readFile(".env")
+
+local env = dotenv:parse(content)
+print(env)
+```
+
+## TODO
+- [x] Basic values
 - [ ] Multiline values
 - [ ] Comments
 - [ ] Variable Substitution