Update README.md

README.md

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-# dotenv
+<h1 align="center"> dotenv 🌴 </h1>
 
 [![CI](https://github.com/dying-will-bullet/dotenv/actions/workflows/ci.yaml/badge.svg)](https://github.com/dying-will-bullet/dotenv/actions/workflows/ci.yaml)
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+
+dotenv is a library that loads environment variables from a `.env` file into `std.os.environ`.
+Storing configuration in the environment separate from code is based on The
+[Twelve-Factor](http://12factor.net/config) App methodology.
+
+This library is a Zig language port of [nodejs dotenv](https://github.com/motdotla/dotenv).
+
+## Quick Start
+
+Automatically find the `.env` file and load the variables into the process environment with just one line.
+
+```zig
+const std = @import("std");
+const dotenv = @import("dotenv");
+
+pub fn main() !void {
+    const allocator = std.heap.page_allocator;
+
+    try dotenv.load(allocator, .{});
+}
+```
+
+By default, it will search for a file named `.env` in the working directory and its parent directories recursively.
+Of course, you can specify a path if desired.
+
+```zig
+pub fn main() !void {
+    try dotenv.loadFrom(allocator, "/app/.env", .{});
+}
+```
+
+**Since writing to `std.os.environ` requires a C `setenv` call, linking with C is necessary.**
+
+If you only want to read and parse the contents of the `.env` file, you can try the following.
+
+```zig
+pub fn main() !void {
+    var envs = try dotenv.getDataFrom(allocator, ".env");
+
+    var it = envs.iterator();
+    while (it.next()) |*entry| {
+        std.debug.print(
+            "{s}={s}\n",
+            .{ entry.key_ptr.*, entry.value_ptr.*.? },
+        );
+    }
+}
+```
+
+This does not require linking with a C library.
+The caller owns the memory, so you need to free both the key and value in the hashmap.
+
+## `.env` Syntax
+
+```
+NAME_1="VALUE_1"
+NAME_2='VALUE_2'
+NAME_3=VALUE_3
+```
+
+#### Multiline values
+
+The value of a variable can span multiple lines(quotes are required).
+
+```
+PRIVATE_KEY="-----BEGIN RSA PRIVATE KEY-----
+ABCD...
+-----END RSA PRIVATE KEY-----"
+```
+
+#### Comments
+
+Comments start with a `#`.
+
+```
+# This is a comment
+NAME="VALUE" # comment
+```
+
+#### Variable Expansion
+
+You can reference a variable using `${}`, and the variable should be defined earlier.
+
+```
+HO="/home"
+ME="/koyori"
+
+HOME="${HO}${ME}"  # equal to HOME=/home/koyori
+```
+
+## LICENSE
+
+MIT License Copyright (c) 2023, Hanaasagi