fix(docs): Correct grammatical errors

[Marcofann]

This PR addresses multiple grammatical errors in comments and documentation across various files in the repository. These changes improve readability and adhere to proper English grammar standards.

Files Changed:

1. staking.go

   • Corrected "a unjail transaction" to "an unjail transaction."

2. Utils.sol

   • Corrected "a operator" to "an operator."

3. slashing.go

   • Corrected similar grammar inconsistencies in generated files.

4. Staking.sol

   • Corrected "an new implementation" to "a new implementation."

5. Upgrade.sol

   • Corrected "an new implementation" to "a new implementation."

6. OmniBridgeNative.sol

   • Corrected "an new implementation" to "a new implementation."

7. validator.md

   • Corrected "a operator private key" to "an operator private key."

8. key.go

   • Corrected "custom a address function" to "custom an address function."