Adds missing particle (#27646)

docs/manual/en/introduction/Libraries-and-Plugins.html

@@ -12,7 +12,7 @@
 		<p class="desc">
 			Listed here are externally developed compatible libraries and plugins for three.js. This
 			list and the associated packages are maintained by the community and not guaranteed
-			to be up to date. If you'd like to update this list make PR!
+			to be up to date. If you'd like to update this list make a PR!
 		</p>
 
 		<h3>Physics</h3>