ethclient: improve documentation comments

[Tinu280]

Minor documentation corrections in ethclient: grammar fixes and clearer wording.
No logic or functional changes included.

[Tinu280]

This PR only updates documentation comments.
The failing test appears to be unrelated to the changes (flaky test in eth/catalyst: TestTrickRemoteBlockCache).
Please advise if any further action is needed.

[Tinu280]

The AppVeyor build is failing on the 32-bit (mingw32) environment, but the 64-bit build and all GitHub Actions checks passed.

This PR only modifies documentation comments and formatting, without touching any logic or platform-specific code.

It seems likely that the AppVeyor 32-bit failure is unrelated to this PR.
Please let me know if there's anything I should adjust, or if the failure can be safely ignored.

Thank you

[Tinu280]

The AppVeyor failure is caused by a time limit timeout on the 32-bit (mingw32) build:

"Build execution time has reached the maximum allowed time for your plan (60 minutes)."

This PR does not modify any logic or platform-specific code, and all GitHub Actions checks have passed successfully.

It seems safe to assume that the timeout is unrelated to the changes in this PR.
Please advise if anything else is needed before approval.

Thank you

[Tinu280]

Hi @gballet, thank you for reviewing.
Could you please advise what was missing or incorrect in this PR so I can improve future contributions?
I’d appreciate any guidance on how to make documentation or code contributions more useful for the project.