Add installation guide

Author: BooleanCat

README.md

@@ -2,7 +2,7 @@
 
 [![GitHub release (with filter)](https://img.shields.io/github/v/release/BooleanCat/go-functional?sort=semver&logo=Go&color=%23007D9C&include_prereleases)](https://github.com/BooleanCat/go-functional/releases) [![Actions Status](https://github.com/BooleanCat/go-functional/workflows/test/badge.svg)](https://github.com/BooleanCat/go-functional/actions) [![Go Reference](https://pkg.go.dev/badge/github.com/BooleanCat/go-functional/v2.svg)](https://pkg.go.dev/github.com/BooleanCat/go-functional/v2) [![Go Report Card](https://goreportcard.com/badge/github.com/BooleanCat/go-functional/v2)](https://goreportcard.com/report/github.com/BooleanCat/go-functional/v2) [![codecov](https://codecov.io/gh/BooleanCat/go-functional/branch/main/graph/badge.svg?token=N2E43RSR14)](https://codecov.io/gh/BooleanCat/go-functional)
 
-A library of iterators for use with `iter.Seq`.
+A library of iterators for use with `iter.Seq`. Requires Go 1.23+.
 
 ```go
 // The first 5 natural numbers
@@ -18,3 +18,9 @@ numbers := it.Map(it.Count(), strconv.Itoa)
 ```
 
 _[Read the docs](https://pkg.go.dev/github.com/BooleanCat/go-functional/v2)_ to see the full iterator library.
+
+## Installation
+
+```terminal
+go get github.com/BooleanCat/go-functional/v2@latest
+```