doc: create maintaining folder for deps

PR-URL: #47589
Refs: nodejs/security-wg#828
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>

Author: marco-ippolito

.github/CODEOWNERS

@@ -146,8 +146,7 @@
 # Single Executable Applications
 /deps/postject @nodejs/single-executable
 /doc/api/single-executable-applications.md @nodejs/single-executable
-/doc/contributing/maintaining-postject.md @nodejs/single-executable
-/doc/contributing/maintaining-single-executable-application-support.md @nodejs/single-executable
+/doc/contributing/maintaining/maintaining-single-executable-application-support.md @nodejs/single-executable
 /src/node_sea* @nodejs/single-executable
 /test/fixtures/postject-copy @nodejs/single-executable
 /test/parallel/test-single-executable-* @nodejs/single-executable