Moving the bulk of redirects to a legacy redirect file in legacy folder (#4256)

* Moving the bulk of redirects to a legacy redirect file in legacy folder

* fix broken link

* resolve conflict

* adding entry to .openpublishing.publish.config.json file

* added missing comma

Author: KathrynEE

.openpublishing.publish.config.json

@@ -92,6 +92,7 @@
   },
   "redirection_files": [
     ".openpublishing.redirection.json",
+    "docs/legacy/.openpublishing.redirection.legacy.json",
     "docs/pipelines/.openpublishing.redirection.pipelines.json"
   ],
   "need_generate_pdf_url_template": true,