Fix multiline table docs and add custom cell sizes section to EN

[X4vi3]

What changed

Russian version (ru/syntax/tables/multiline.md)

• Fixed the cell width/height syntax. Replaced {width=400px} and {height=100px} with the correct {style="width: 400px"} and {style="height:100px"}.
• Fixed typos in the in-cell list example: "Текс 1" → "Текст 1", "Тект 2" → "Текст 2".
• Removed a stray artifact — an accidental link to a local file (cell_merging_guide.md).

English version (en/syntax/tables/multiline.md)

• Added the "Custom cell sizes" section describing how to set cell width and height. It previously existed only in the Russian version, so EN and RU are now in parity.

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