chore: add .gitleaks.toml to allowlist doc placeholders

The curl-auth-header rule flags the example `curl -H "Authorization:
Bearer YOUR_PASSWORD"` command in docs/troubleshooting.md as a secret.
This is a false positive — YOUR_PASSWORD is a placeholder, not a real
credential. Allowlist the path to suppress the finding.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: dorlugasigal

.gitleaks.toml

@@ -0,0 +1,5 @@
+[allowlist]
+description = "Allow example/placeholder credentials in documentation"
+paths = [
+  '''docs/troubleshooting\.md''',
+]