Update README.md

Author: fedorovvvv

README.md

@@ -5,7 +5,7 @@
 ## Installation
 
 ```bash
-npm i svelte-floating-ui
+npm i -D svelte-floating-ui
 ```
 
 This is not yet published on npm
@@ -136,4 +136,4 @@ To set the styles, you can pass the [`onComputed`](#applying-custom-styles-on-co
     <div class="arrow" bind:this={$arrowRef} />
   </div>
 {/if}
-```
+```