Typo fix Update README.md

[VitalikBerashvili]

Details of the Fix:
Original text: "apis-staging.exmaple.json"
Corrected text: "apis-staging.example.json"
Explanation:
The word "exmaple" was a typo and was corrected to "example."
This fix ensures that the file name is spelled correctly, helping to avoid confusion for developers or users following the documentation.
Change Summary:
File affected: README.md
Lines affected: Line 41
Number of changes: One deletion (incorrect text) and one addition (corrected text).

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