[repo] Update list of obsolete pages

Author: andrewnicols

data/obsoletePages.json

@@ -449,7 +449,6 @@
   "Moodle Workplace 3.8 release notes",
   "Moodle Workplace 3.9 release notes",
   "Moodle Workplace 4.0 release notes",
-  "Moodle Workplace releases",
   "Moodle and PHP 7.0 details",
   "Moodle dev mailing list",
   "Moodle forms library",