docs(cn): remove datadog from sidebar & fix doc lint conf (#6411)

Author: spacewander

.github/workflows/doc-lint.yml

@@ -4,6 +4,7 @@ on:
   pull_request:
     branches: [master, 'release/**']
     paths:
+      - 'docs/**'
       - '**/*.md'
 
 jobs:

docs/zh/latest/config.json

@@ -117,8 +117,7 @@
               "label": "Metrics",
               "items": [
                 "plugins/prometheus",
-                "plugins/node-status",
-                "plugins/datadog"
+                "plugins/node-status"
               ]
             },
             {