docs: Fix variable name according to the example

[Elias-Black]

No description provided.

[mergeable]

Hi there, Elias-Black! 👋

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[neznaika0]

Good Point, the correction is unqualified.

CodeIgniter4/system/BaseModel.php

Line 634 in 686e9ae

public function findColumn(string $columnName)

Do you want to find other errors that don't match the code? 😄 Example, Forge::dropColumn() Forge::dropTable() in forge.rst: php:method:: dropTable($table_name[, $if_exists = false])

[michalsn]

@Elias-Black Thank you and congratulations on your first PR!