Typo Update validator-offline.md

[voronor]

Grammatical error in the sentence:

Before:
"there are no penalties or slashing that occurs from a missed block proposal"

After:
"there are no penalties or slashing that occur from a missed block proposal"

Explanation:
The error was caused by the subject "penalties or slashing," which is plural, so the verb should be "occur" instead of "occurs." Correcting this improves the readability and grammatical accuracy of the sentence.

Importance:
While this is a relatively minor grammatical fix, it ensures that the text is clear and professional, particularly for users relying on precise language in technical documentation. Using the correct verb form avoids confusion and maintains consistency throughout the documentation.