Add a readme

Author: karngyan

README.md

@@ -1,11 +1,78 @@
 # sx
 
-[![Go Reference](https://pkg.go.dev/badge/github.com/gomantics/sx.svg)](https://pkg.go.dev/github.com/gomantics/sx)
+[![Go Reference](https://pkg.go.dev/badge/github.com/gomantics/sx.svg)](https://pkg.go.dev/github.com/gomantics/sx) [![CI](https://github.com/gomantics/sx/actions/workflows/ci.yml/badge.svg)](https://github.com/gomantics/sx/actions/workflows/ci.yml)
 
-TODO Description
+A simple Go library for string case conversion. Converts between camelCase, PascalCase, kebab-case, snake_case, and more.
 
 ## Installation
 
 ```bash
 go get github.com/gomantics/sx
 ```
+
+## Usage
+
+```go
+package main
+
+import (
+    "fmt"
+
+    "github.com/gomantics/sx"
+)
+
+func main() {
+    // Convert to different cases
+    fmt.Println(sx.CamelCase("hello-world"))     // helloWorld
+    fmt.Println(sx.PascalCase("hello_world"))    // HelloWorld
+    fmt.Println(sx.KebabCase("HelloWorld"))      // hello-world
+    fmt.Println(sx.SnakeCase("HelloWorld"))      // hello_world
+    fmt.Println(sx.TrainCase("hello-world"))     // Hello-World
+    fmt.Println(sx.FlatCase("hello-world"))      // helloworld
+
+    // Works with mixed separators and cases
+    fmt.Println(sx.CamelCase("mixed_caseWith-different.separators"))  // mixedCaseWithDifferentSeparators
+
+    // Handle complex acronyms
+    fmt.Println(sx.KebabCase("XMLHttpRequest"))  // xml-http-request
+    fmt.Println(sx.CamelCase("HTML5Parser"))     // html5Parser
+}
+```
+
+## Case Functions
+
+- `CamelCase()` - converts to camelCase
+- `PascalCase()` - converts to PascalCase
+- `KebabCase()` - converts to kebab-case
+- `SnakeCase()` - converts to snake_case
+- `TrainCase()` - converts to Train-Case
+- `FlatCase()` - converts to flatcase (no separators)
+
+## Utilities
+
+- `SplitByCase()` - splits strings into words by case changes and separators
+- `UpperFirst()` - capitalizes first character
+- `LowerFirst()` - lowercases first character
+
+## Options
+
+Some functions support options for customization:
+
+```go
+// Normalize case for strict PascalCase/camelCase
+sx.PascalCase("XMLHttpRequest", sx.WithNormalize(true))  // XmlHttpRequest
+
+// Custom separators for splitting
+sx.SplitByCase("hello.world", sx.WithSeparators('.'))  // ["hello", "world"]
+
+// Custom separator for kebab case
+sx.KebabCase("hello world", "|")  // hello|world
+```
+
+## Contributing
+
+Contributors are always welcome! Feel free to raise a PR or create an issue first.
+
+## License
+
+MIT