fix(schema): remove duplicate example entry

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

Author: pan93412

schema/zbpack.json

@@ -123,7 +123,6 @@
                     "examples": [
                         "Dockerfile",
                         "/Dockerfile",
-                        "/docker/custom.Dockerfile",
                         "/docker/custom.Dockerfile"
                     ]
                 }