Fix broken links (#280)

Author: fmerian

advanced/rest-api/overview.mdx

@@ -14,7 +14,7 @@ functionality to the API overtime. Let us know what else you want to see in
 ## Authentication
 
 You can generate an API key through
-[the dashboard](https://dashboard.mintlify.com/settings/api). The API key is
+[the dashboard](https://dashboard.mintlify.com/settings/integrations). The API key is
 associated with the entire org and can be used across multiple deployments.
 
 <Frame>

images/external-api-key.png

@@ -621,12 +621,12 @@ Click on the following dropdown to view a sample configuration file
   ],
   "footerSocials": {
     "github": "https://github.com/mintlify",
-    "discord": "https://discord.gg/MPNgtSZkgK",
+    "slack": "https://mintlify.com/community",
     "x": "https://x.com/mintlify"
   },
   "integrations": {
-    "intercom": "abcdefz",
-    "frontchat": "abcdez"
+    "intercom": "APP_ID",
+    "frontchat": "CHAT_ID"
   }
 }
 ```
@@ -636,4 +636,4 @@ Click on the following dropdown to view a sample configuration file
 ## More Customization
 
 Learn more about how to further customize your docs with custom CSS and JS in
-[Custom Scripts](https://mintlify.com/docs/integrations/custom/).
+[Custom Scripts](https://mintlify.com/docs/advanced/custom/).