Add $PROMPT variable to issue_body description in CI docs (#13)

Co-authored-by: promptless[bot] <179508745+promptless[bot]@users.noreply.github.com>

Author: promptless[bot]

fern/pages/docs/get-started/ci.mdx

@@ -119,7 +119,7 @@ jobs:
 |-------|---------|-------------|
 | `create_issue_on_fail` | `false` | Create an issue if tests fail |
 | `issue_title` | `Doc Detective Failure` | Issue title |
-| `issue_body` | See default | Issue body (`$RESULTS` inserts test results, `$RUN_URL` inserts workflow URL) |
+| `issue_body` | See default | Issue body (`$RESULTS` inserts test results, `$RUN_URL` inserts workflow URL, `$PROMPT` inserts the prompt text) |
 | `issue_labels` | `doc-detective` | Comma-separated labels |
 | `issue_assignees` | None | Comma-separated usernames to assign |
 | `integrations` | None | Comma-separated integrations to trigger (see [Integrations](/docs/get-started/integrations)) |