doc: Add additional SQL features codes from SQL:2023

These were mysteriously omitted in c9f5754.

Author: petere

src/backend/catalog/sql_features.txt

@@ -348,6 +348,7 @@ F865	<offset row count> in <result offset clause>			YES
 F866	FETCH FIRST clause: PERCENT option			NO	
 F867	FETCH FIRST clause: WITH TIES option			YES	
 F868	ORDER BY in grouped table			YES	
+F869	SQL implementation info population			YES	
 R010	Row pattern recognition: FROM clause			NO	
 R020	Row pattern recognition: WINDOW clause			NO	
 R030	Row pattern recognition: full aggregate support			NO	
@@ -425,6 +426,7 @@ T054	GREATEST and LEAST			YES	different null handling
 T055	String padding functions			YES	
 T056	Multi-character TRIM functions			YES	
 T061	UCS support			NO	
+T062	Character length units			NO	
 T071	BIGINT data type			YES	
 T076	DECFLOAT data type			NO	
 T081	Optional string types maximum length			YES