Fix Typos in Documentation Files

[Dimitrolito]

This pull request addresses minor typographical errors in three documentation files. Below are the specific changes made:

1. eth_gasPrice.md

   • Fixed article usage in reference to EIP-1559 transactions.

2. rpc_api_status.md

   • Added a missing article ("a new") for clarity and grammatical correctness in the description of the eth_sendTransaction method.

3. README.md

   • Corrected "above mentioned" to "above-mentioned" to follow proper hyphenation rules for compound adjectives.

These changes improve the readability and grammatical accuracy of the documentation.

Pull Request type

• Documentation content changes

Does this introduce a breaking change?

• Yes
• No