website/integrations: Correct Discord avatar code and add warning. (#…

…11031)

There's a mispelling which causes the avatar gathered to not be the desired size.

Additionally, larger avatars appear to cause "Header too large" errors when users attempt to access services (at least for me via a proxy providers.)

This can also be seen users have a very large JWT in their request headers. (You can use https://github.com/traefik/whoami for debugging).

Signed-off-by: Aterfax <Aterfax@users.noreply.github.com>

website/docs/sources/discord/index.md

@@ -327,10 +327,10 @@ Create a new **Expression Policy** with the content below, adjusting the variabl
 import base64
 import requests
 
-AVATAR_SIZE = "64"  # Valid values: 16,32,64,128,256,512,1024
+AVATAR_SIZE = "64"  # Valid values: 16,32,64,128,256,512,1024. Larger values may cause HTTP error 431 on applications/providers due to headers being too large.
 
 # Only change below here if you know what you are doing.
-AVATAR_URL = "https://cdn.discordapp.com/avatars/{id}/{avatar}.png?site={avatar_size}"
+AVATAR_URL = "https://cdn.discordapp.com/avatars/{id}/{avatar}.png?size={avatar_size}"
 AVATAR_STREAM_CONTENT = "data:image/png;base64,{base64_string}"  # Converts base64 image into html syntax usable with authentik's avatar attributes feature