Exclude legacy files from build scope

Author: Saisang

docfx.json

@@ -37,7 +37,7 @@
           "**/includes/**",
           "**/*-index.md"
         ],
-        "src": "api/overview/azure/legacy",
+        "src": "api/overview/azure/legacy-redirects-temp",
         "dest": "api/overview/azure",
         "group": "legacy"
       },
@@ -955,4 +955,4 @@
     "lruSize": 0,
     "debug": true
   }
-}
+}