docs: fix wrong topic (supabase#42641)

Builds were failing with zod error introduced here:
supabase#42464

```
Error:Error [ZodError]: [
  {
    "received": "data api",
    "code": "invalid_enum_value",
    "options": [
      "ai",
      "auth",
      "branching",
      "cli",
      "database",
      "functions",
      "platform",
      "realtime",
      "self-hosting",
      "storage",
      "studio",
      "supavisor",
      "terraform"
    ],
    "path": [
      "topics",
      1
    ],
    "message": "Invalid enum value. Expected 'ai' | 'auth' | 'branching' | 'cli' | 'database' | 'functions' | 'platform' | 'realtime' | 'self-hosting' | 'storage' | 'studio' | 'supavisor' | 'terraform', received 'data api'"
  }
]
```

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Documentation**
* Updated documentation categorization for troubleshooting content to
improve discoverability.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: mandarini

apps/docs/content/troubleshooting/postgrest-not-recognizing-new-columns-or-functions-bd75f5.mdx

@@ -1,6 +1,6 @@
 ---
 title = "PostgREST not recognizing new columns, tables, views or functions"
-topics = [ "cli", "data api", "database", "functions" ]
+topics = [ "cli", "platform", "database", "functions" ]
 keywords = []
 ---