docs: typo fix Update cairo_precompiles.md

[mdqst]

Description

I noticed a small grammatical issue in the documentation regarding the Cairo precompiles section. The sentence:

"The selector of the Cairo function being called should always be present in the contract called."

was a bit awkward and not quite in line with proper English syntax. It should read:

"The selector of the Cairo function being called should always be present in the called contract."

The change was made to correct the word order and ensure clarity.

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
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• Documentation content changes
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