Add new translation variables for GND entity encoding headings

nodac/en/gnd_entities.json

@@ -47,6 +47,9 @@
         "sxz": "Ficticious keywords",
         "szz": "Unknown cases",
         "vie": "Congresses, events",
-        "vif": "Congress series, event series"
+        "vif": "Congress series, event series",
+        "k": "Institutions and bodies",
+        "s": "Keywords",
+        "p": "Families and Persons"
     }
 }