Sort docs alphabetically

Author: jobselko

docs/user/guides/_SUMMARY.md

@@ -1,8 +1,8 @@
+* [Attestation Hosting](attestation.md)
+* [Host Python Content](host.md)
+* [Package Blocklist](blocklist.md)
+* [Package Substitution](package_substitution.md)
 * [Set up your own PyPI](pypi.md)
 * [Sync from Remote Repositories](sync.md)
 * [Upload and Manage Content](upload.md)
-* [Host Python Content](host.md)
 * [Vulnerability Report](vulnerability_report.md)
-* [Attestation Hosting](attestation.md)
-* [Package Blocklist](blocklist.md)
-* [Package Substitution](package_substitution.md)