Document window functions implemented in 10.2

Window functions pages in https://mariadb.com/kb/en/library/window-functions/ do not mention the following functions:
LAG()
LEAD()
NTH_VALUE()
LAST_VALUE()

All of them are working in 10.2.10
{{CREATE TABLE t (x INT);
INSERT INTO t VALUES(1),(3),(2);
SELECT x, LAG OVER() lag, LEAD OVER() lead, NTH_VALUE(x, 1) OVER() first, LAST_VALUE OVER() last FROM t;
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3 rows in set (0.00 sec)

SELECT @@version;
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1 row in set (0.00 sec)}}