docs(README) Add detailed documentation

README.md

@@ -1,7 +1,47 @@
+![Logo](./is-thirteen-logo.png)
+
 # is-thirteen
 
 [![go.dev reference](https://img.shields.io/badge/go.dev-reference-007d9c)](https://pkg.go.dev/github.com/stanleynguyen/is-thirteen)
 ![](https://github.com/stanleynguyen/is-thirteen/workflows/test/badge.svg)
 ![](https://github.com/stanleynguyen/is-thirteen/workflows/lint/badge.svg)
 
-Check if a number is equal to 13.
+Check if a number is equal to 13. A port of [this NPM module](https://github.com/jezen/is-thirteen).
+
+## Installation
+
+```bash
+go get -u github.com/stanleynguyen/is-thirteen
+```
+
+## Usage
+
+```go
+package main
+
+import "github.com/stanleynguyen/is-thirteen"
+
+func main() {
+	is.Number(13).Thirteen()               // true
+	is.Number(12.8).Roughly.Thirteen()     // true
+	is.Number(6).Within(10).Of.Thirteen()  // true
+	is.Number(2007).YearOfBirth.Thirteen() // true
+
+	// check your math skillz
+	is.Number(4).Plus(5).Thirteen()     // false
+	is.Number(12).Plus(1).Thirteen()    // true
+	is.Number(4).Minus(12).Thirteen()   // false
+	is.Number(14).Minus(1).Thirteen()   // true
+	is.Number(1).Times(8).Thirteen()    // false
+	is.Number(26).Divides(2).Thirteen() // true
+
+	// check your spelling and chemistry skillz
+	is.String("tHirTeEn").Thirteen()              // true
+	is.String("nethtire").AnagramOf.Thirteen()    // true
+	is.String("neetriht").Backwards.Thirteen()    // true
+	is.String("aLumInUm").AtomicNumber.Thirteen() // true
+}
+
+```
+
+Check out [pkg.go.dev](https://pkg.go.dev/github.com/stanleynguyen/is-thirteen) for the full documentation.