add readme badge to document minimum svelte version (for #24)

Author: janosh

netlify.toml

@@ -3,7 +3,7 @@ command = "yarn build"
 publish = "build"
 
 [build.environment]
-NODE_VERSION = "17.0.1"
+NODE_VERSION = "17.4.0"
 YARN_VERSION = "1.22.11"
 
 # https://plausible.io/docs/proxy/guides/netlify

readme.md

@@ -8,6 +8,7 @@
 [![Netlify Status](https://api.netlify.com/api/v1/badges/a45b62c3-ea45-4cfd-9912-77ec4fc8d7e8/deploy-status)](https://app.netlify.com/sites/svelte-multiselect/deploys)
 [![NPM version](https://img.shields.io/npm/v/svelte-multiselect?color=blue&logo=NPM)](https://npmjs.com/package/svelte-multiselect)
 [![pre-commit.ci status](https://results.pre-commit.ci/badge/github/janosh/svelte-multiselect/main.svg)](https://results.pre-commit.ci/latest/github/janosh/svelte-multiselect/main)
+![Needs Svelte version](https://img.shields.io/npm/dependency-version/svelte-multiselect/dev/svelte)
 
 </h4>