docs: add release badge

Author: matzehuels

README.md

@@ -2,6 +2,7 @@
 
 [![CI](https://github.com/matzehuels/stacktower/actions/workflows/ci.yml/badge.svg)](https://github.com/matzehuels/stacktower/actions/workflows/ci.yml)
 [![Go Report Card](https://goreportcard.com/badge/github.com/matzehuels/stacktower)](https://goreportcard.com/report/github.com/matzehuels/stacktower)
+[![Release](https://img.shields.io/github/v/release/matzehuels/stacktower)](https://github.com/matzehuels/stacktower/releases)
 [![License](https://img.shields.io/badge/License-Apache_2.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
 
 Inspired by [XKCD #2347](https://xkcd.com/2347/), Stacktower renders dependency graphs as **physical towers** where blocks rest on what they depend on. Your application sits at the top, supported by libraries below—all the way down to that one critical package maintained by *some dude in Nebraska*.