docs(WIP): Bring the main doc pages up to date, and add more examples (#2094)

* Bring some docs up to date, as well as add a new example

* Missed an exclamation mark

* Do requested changes

* Do suggestions

* Same suggestions for the other examples

* Show people that they can also use reply with embeds

* Typos in embed.js example

* Remove object example from embeds, too complex
Suggested by Yukine

* Some changes, some requested changes

* Add moderation examples!

* Add attachment examples

* Missing dot

* Fix spacing

* Requested Changes

* Quote consistency

* Tfw you break the syntax

docs/index.yml

@@ -18,7 +18,13 @@
       path: ping.js
     - name: Avatars
       path: avatars.js
+    - name: Attachments
+      path: attachments.md
     - name: Server greeting
       path: greeting.js
+    - name: Message Embed
+      path: embed.js
+    - name: Moderation
+      path: moderation.md
     - name: Webhook
       path: webhook.js