Update to new Glint addon best practices

The Glint docs now recommend to export the Registry, see https://typed-ember.gitbook.io/glint/using-glint/ember/authoring-addons

README.md

@@ -150,6 +150,30 @@ var app = new EmberApp(defaults, {
 
 [Click here for more configuration options](#configuration)
 
+### TypeScript usage
+
+The `svg-jar` helper has proper [Glint](https://github.com/typed-ember/glint) types, which allow you when using TypeScript to get strict type checking in your templates.
+
+Unless you are using [strict mode](http://emberjs.github.io/rfcs/0496-handlebars-strict-mode.html) templates (via [first class component templates](http://emberjs.github.io/rfcs/0779-first-class-component-templates.html)),
+you need to import the addon's Glint template registry and `extend` your app's registry declaration as described in the [Using Addons](https://typed-ember.gitbook.io/glint/using-glint/ember/using-addons#using-glint-enabled-addons) documentation:
+
+```ts
+import '@glint/environment-ember-loose';
+
+import type EmberSvgJarRegistry from 'ember-svg-jar/template-registry';
+
+declare module '@glint/environment-ember-loose/registry' {
+  export default interface Registry
+    extends EmberSvgJarRegistry /* other addon registries */ {
+    // local entries
+  }
+}
+```
+
+Should you want to manage the registry by yourself, then omit this import, and instead add the entries in your app by explicitly importing the types of the helper from this addon.
+
+> Note that Glint itself is still under active development, and as such breaking changes might occur. Therefore, Glint support by this addon is also considered experimental, and not covered by our SemVer contract!
+
 ### Usage in an addon
 
 Using `ember-svg-jar` in an addon is the same as in an app, except that in the `package.json`

packages/ember-svg-jar/addon/template-registry.d.ts

@@ -0,0 +1,6 @@
+import type SvgJar from './types';
+
+export default interface EmberSvgJarRegistry {
+  'svg-jar': typeof SvgJar;
+  svgJar: typeof SvgJar;
+}