chore: update discord urls (discordjs#400)

Author: WiseDevHelper

guide/preparations/adding-your-bot-to-servers.md

@@ -9,7 +9,7 @@ Before you're actually able to see your bot in your own (or other) servers, it n
 The basic version of one such link looks like this:
 
 ```
-https://discordapp.com/oauth2/authorize?client_id=123456789012345678&scope=bot
+https://discord.com/oauth2/authorize?client_id=123456789012345678&scope=bot
 ```
 
 The structure of the url is quite simple:
@@ -28,7 +28,7 @@ If you get an error message saying "Bot requires a code grant", then head over i
 
 ## Creating and using your own invite link
 
-As mentioned above, you'll need to replace the `client_id` parameter with your client's ID in order to generate your invite link. To find your app's ID, head back to the [My Apps](https://discordapp.com/developers/applications/me) page under the "Applications" section once again and click on your bot application.
+As mentioned above, you'll need to replace the `client_id` parameter with your client's ID in order to generate your invite link. To find your app's ID, head back to the [My Apps](https://discord.com/developers/applications/me) page under the "Applications" section once again and click on your bot application.
 
 Insert your app's ID into the link template and then access it in your browser. You should see something like this (with your bot's username and avatar):