Typo fix testnet.md

[teenager-ETH]

Typo Fix in testnet.md

Description

Corrected the following typos for improved clarity and professionalism:

• Changed "Offical" to "Official."
• Adjusted minor formatting by adding a space after a period for readability.

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This PR is ready for review. ✅

[sonarqubecloud[bot]]

Quality Gate passed

Issues
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0 Accepted issues

Measures
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0.0% Coverage on New Code
0.0% Duplication on New Code

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