RFR: Improve English grammar in error messages

[Aleksey Shipilev]

On Sat, 27 Nov 2021 15:20:03 GMT, Aarre Laakso <duke at openjdk.java.net> wrote:

> I improved the English grammar in a few error messages

I have a minor suggestion.

Also, please change the PR title to "7903067: JMH: Improve English grammar in error messages" to get bots active here.

.gitignore line 3:

> 1: *.iml
> 2: target/
> 3: .idea/

This change is irrelevant, let's revert it.

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Changes requested by shade (Committer).

PR: https://git.openjdk.java.net/jmh/pull/56