Refer to Datastore everywhere correctly by its capitalized form

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=147479683

java/google/registry/whois/WhoisResponseImpl.java

@@ -150,7 +150,7 @@ abstract class WhoisResponseImpl implements WhoisResponse {
     /** Returns raw text that should be appended to the end of ALL WHOIS responses. */
     E emitLastUpdated(DateTime timestamp) {
       // We are assuming that our WHOIS database is always completely up to date, since it's
-      // querying the live backend datastore.
+      // querying the live backend Datastore.
       stringBuilder
           .append(">>> Last update of WHOIS database: ")
           .append(UtcDateTimeAdapter.getFormattedString(timestamp))