add links to gulp/Metalsmith plugins

gulp-svelte
https://github.com/shinnn/gulp-svelte
https://www.npmjs.com/package/gulp-svelte

metalsmith-svelte
https://github.com/shinnn/metalsmith-svelte
https://www.npmjs.com/package/metalsmith-svelte

README.md

@@ -9,6 +9,8 @@ This is the Svelte compiler, which is primarily intended for authors of tooling
 * [svelte-cli](https://github.com/sveltejs/svelte-cli) – Command line interface for compiling components
 * [rollup-plugin-svelte](https://github.com/rollup/rollup-plugin-svelte) – Rollup plugin
 * [sveltify](https://github.com/tehshrike/sveltify) - Browserify transform
+* [gulp-svelte](https://github.com/shinnn/gulp-svelte) - gulp plugin
+* [metalsmith-svelte](https://github.com/shinnn/metalsmith-svelte) - Metalsmith plugin
 * More to come!