Update configuration.adoc

[OlliTietavainenVaadin]

Clarified the language of the Core & Pro Vaadin React Components chapter

[github-actions]

AI Language Review

The updated file, configuration, contains the following issues that require improvement:

1. In the sentence describing the @vaadin/react-components-pro package, remove the extra word "is" for grammatical correctness: change "which is contains only commercial components" to "which contains only commercial components."

2. The sentence "Vaadin adds both of these packages to [filename]package.json if the com.vaadin:vaadin artifact is used in the project configuration" could clarify what "project configuration" refers to. Consider specifying whether this is a Maven setup, npm configuration, or another system.

3. In the headings and titles, ensure consistent capitalization: change "Vaadin React Components" to "Vaadin React Components" to align with title case rules. This is already correct in the updated file, so it’s important to maintain consistency in further documents.

Overall, these adjustments will enhance clarity and grammatical accuracy.