Improve grammar and parallel structure in React library documentation

[dileepdhangar]

Summary This pull request aims to improve the grammar and parallel structure in the documentation for the React library. The motivation behind this change is to enhance readability and clarity for users accessing the documentation.

To test this change, I reviewed the modified documentation to ensure that the grammar improvements were correctly implemented. Specifically, I focused on the Declarative section where the changes were made. I carefully checked for any grammatical errors or inconsistencies and verified that the revised text maintains coherence and clarity.

Additionally, I ran a spell check to ensure that there were no spelling errors introduced during the modification process.

No changes were made to the code functionality; therefore, no additional testing beyond reviewing the documentation was necessary for this specific change.