Add tab completion for EXPLAIN (MEMORY|SERIALIZE)

SERIALIZE has been added in 06286709ee, and MEMORY in 5de890e361.

Author: Jian He
Discussion: https://postgr.es/m/CACJufxH5UbhbCg-oMt7pHOmvNABF2x48Jfefu24FexSqVgzA3g@mail.gmail.com

src/bin/psql/tab-complete.c

@@ -3870,9 +3870,12 @@ psql_completion(const char *text, int start, int end)
 		 */
 		if (ends_with(prev_wd, '(') || ends_with(prev_wd, ','))
 			COMPLETE_WITH("ANALYZE", "VERBOSE", "COSTS", "SETTINGS", "GENERIC_PLAN",
-						  "BUFFERS", "WAL", "TIMING", "SUMMARY", "FORMAT");
-		else if (TailMatches("ANALYZE|VERBOSE|COSTS|SETTINGS|GENERIC_PLAN|BUFFERS|WAL|TIMING|SUMMARY"))
+						  "BUFFERS", "SERIALIZE", "WAL", "TIMING", "SUMMARY",
+						  "MEMORY", "FORMAT");
+		else if (TailMatches("ANALYZE|VERBOSE|COSTS|SETTINGS|GENERIC_PLAN|BUFFERS|WAL|TIMING|SUMMARY|MEMORY"))
 			COMPLETE_WITH("ON", "OFF");
+		else if (TailMatches("SERIALIZE"))
+			COMPLETE_WITH("TEXT", "NONE", "BINARY");
 		else if (TailMatches("FORMAT"))
 			COMPLETE_WITH("TEXT", "XML", "JSON", "YAML");
 	}