Fix system prompt injection description and title

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: BazookaMusic

javascript/ql/src/Security/CWE-1427/SystemPromptInjection.ql

@@ -1,5 +1,6 @@
 /**
- * @name Prompt injection
+ * @name System prompt injection
+ * @description Untrusted input flowing into a system prompt, developer prompt, or tool description of an AI model may allow an attacker to manipulate the model's behavior.
  * @kind path-problem
  * @problem.severity error
  * @security-severity 5.0