Too long rule number causes an Invalid Form Body error
Sentry Issue: [BOT-1QT](https://sentry.io/organizations/python-discord/issues/2809844874/?referrer=github_integration)

```
HTTPException: 400 Bad Request (error code: 50035): Invalid Form Body
In content: Must be 2000 or fewer in length.
  File "discord/ext/commands/core.py", line 167, in wrapped
    ret = await coro(*args, **kwargs)
  File "bot/exts/info/site.py", line 129, in site_rules
    await ctx.send(f":x: Invalid rule indices: {invalid}")
  File "discord/abc.py", line 1422, in send
    data = await state.http.send_message(
  File "discord/http.py", line 335, in request
    raise HTTPException(response, data)

Error executing command invoked by [READCTED]: !rule 100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000...
```
diff --git a/bot/exts/info/site.py b/bot/exts/info/site.py
index e8e71558..bcb04c90 100644
--- a/bot/exts/info/site.py
+++ b/bot/exts/info/site.py
@@ -1,3 +1,5 @@
+from textwrap import shorten
+
 from discord import Colour, Embed
 from discord.ext.commands import Cog, Context, Greedy, group
 
@@ -123,7 +125,8 @@ class Site(Cog):
 
         # Remove duplicates and sort the rule indices
         rules = sorted(set(rules))
-        invalid = ', '.join(str(index) for index in rules if index < 1 or index > len(full_rules))
+        invalid = shorten(', '.join(str(index) for index in rules if index
+                          < 1 or index > len(full_rules)), 50, placeholder='...')
 
         if invalid:
             await ctx.send(f":x: Invalid rule indices: {invalid}")
['bot/exts/info/site.py']