Add comments linking pg_strftime to timestamptz_to_str

src/backend/utils/adt/timestamp.c

@@ -1738,6 +1738,8 @@ timestamptz_to_time_t(TimestampTz t)
  * This is mostly for use in emitting messages.  The primary difference
  * from timestamptz_out is that we force the output format to ISO.  Note
  * also that the result is in a static buffer, not pstrdup'd.
+ *
+ * See also pg_strftime.
  */
 const char *
 timestamptz_to_str(TimestampTz t)

src/timezone/strftime.c

@@ -118,6 +118,12 @@ static char *_fmt(const char *, const struct pg_tm *, char *, const char *,
 static char *_yconv(int, int, bool, bool, char *, char const *);
 
 
+/*
+ * Convert timestamp t to string s, a caller-allocated buffer of size maxsize,
+ * using the given format pattern.
+ *
+ * See also timestamptz_to_str.
+ */
 size_t
 pg_strftime(char *s, size_t maxsize, const char *format, const struct pg_tm *t)
 {