add docs

src/runtime/internal/Component.ts

@@ -212,6 +212,9 @@ if (typeof HTMLElement === 'function') {
 	};
 }
 
+/**
+ * Base class for Svelte components. Used when dev=false.
+ */
 export class SvelteComponent {
 	$$: T$$;
 	$$set?: ($$props: any) => void;

src/runtime/internal/dev.ts

@@ -104,7 +104,9 @@ export interface SvelteComponentDev {
 	$destroy(): void;
 	[accessor: string]: any;
 }
-
+/**
+ * Base class for Svelte components with some minor dev-enhancements. Used when dev=true.
+ */
 export class SvelteComponentDev extends SvelteComponent {
 	/**
 	 * @private
@@ -151,6 +153,29 @@ export interface SvelteComponentTyped<
 	$destroy(): void;
 	[accessor: string]: any;
 }
+/**
+ * Base class to create strongly typed Svelte components.
+ * This only exists for typing purposes and should be used in `.d.ts` files.
+ * 
+ * Example:
+ * 
+ * You have component library on npm called `component-library`, from which
+ * you export a component called `MyComponent`. For Svelte+TypeScript users,
+ * you want to provide typings. Therefore you create a `index.d.ts`:
+ * ```ts
+ * import { SvelteComponentTyped } from "svelte";
+ * export class MyComponent extends SvelteComponentTyped<{foo: string}> {}
+ * ```
+ * Typing this makes it possible for IDEs like VS Code with the Svelte extension
+ * to provide intellisense and to use the component like this in a Svelte file
+ * with TypeScript:
+ * ```svelte
+ * <script lang="ts">
+ * 	import { MyComponent } from "component-library";
+ * </script>
+ * <MyComponent foo={'bar'} />
+ * ```
+ */
 export class SvelteComponentTyped<
 	Props extends Record<string, any> = any,
 	Events extends Record<string, any> = any,