Types: include a template registry and README notes

Co-authored-by: V. Lascik <vlascik@users.noreply.github.com>

README.md

@@ -237,6 +237,23 @@ Usage:
 </Root>
 ```
 
+## Glint usage
+If you are using [Glint](https://typed-ember.gitbook.io/glint/) and `environment-ember-loose`, you can add all the modifiers to your app at once by adding
+
+```ts
+import type RenderModifiersRegistry from '@ember/render-modifiers/template-registry';
+```
+to your app's e.g. `types/glint.d.ts` file, and making sure your registry extends from RenderModifiersRegistry:
+
+```ts
+declare module '@glint/environment-ember-loose/registry' {
+  export default interface Registry
+    extends RenderModifiersRegistry {
+      // ...
+    }
+}
+```
+
 ## Contributing
 
 See the [Contributing](CONTRIBUTING.md) guide for details.

types/template-registry.d.ts

@@ -0,0 +1,9 @@
+import type didInsert from './modifiers/did-insert';
+import type didUpdate from './modifiers/did-update';
+import type willDestroy from './modifiers/will-destroy';
+
+export default interface RenderModifiersRegistry {
+  'did-insert': typeof didInsert;
+  'did-update': typeof didUpdate;
+  'will-destroy': typeof willDestroy;
+}