[fix](doc) v2.1/v3.x: correct ARRAY_ENUMERATE_UNIQ multi-array example result

[boluor]

Problem

The multi-array example

select array_enumerate_uniq([1,1,1,1,1],[2,1,2,1,2],[3,1,3,1,3]);

is documented as [1, 1, 2, 1, 3], which is wrong. array_enumerate_uniq returns, for each position, the ordinal of that position's tuple among equal tuples. The by-position tuples here are:

(1,2,3) (1,1,1) (1,2,3) (1,1,1) (1,2,3)

so the ordinals are [1, 1, 2, 2, 3] — the 4th position is the 2nd occurrence of (1,1,1), not the 1st. The doc had 1 at the 4th position.

Scope

Present (and fixed) in v2.1 EN, v3.x EN, v3.x ZH. Already correct in v2.1 ZH, v4.x, and dev, so those are untouched.

This page's other examples are correct (checked by hand and on cluster): the single-array example [1,2,3,1,2,3] → [1,1,1,2,2,2] and the description prose [1,2,1,1,2],[2,1,2,2,1] → [1,1,2,3,2].

Note: this is a "both languages wrong" case on v3.x, so a cross-language diff doesn't reveal it — it was caught by a native v2.1 sweep where v2.1 ZH happened to already be correct.

Cluster verification (Doris 3.1.4-rc02 and 2.1.11-rc01, identical)

mysql> select array_enumerate_uniq([1, 1, 1, 1, 1], [2, 1, 2, 1, 2], [3, 1, 3, 1, 3]);
+-------------------------------------------------------------------------+
| array_enumerate_uniq([1, 1, 1, 1, 1], [2, 1, 2, 1, 2], [3, 1, 3, 1, 3]) |
+-------------------------------------------------------------------------+
| [1, 1, 2, 2, 3]                                                         |
+-------------------------------------------------------------------------+

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