React Hooks: changed confusing phrasing about 'useEffect' and ESLint

[marcodallagatta]

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1. Because: Wording was confused and probably a result of a copy paste error.

2. This PR:

• The dependency array at the end is optional, however, you will include it more often than not. A dependency is any state, prop, context that is used within the useEffect callback. You can also include state or props that are not. === becomes === The dependency array at the end is optional, however, you will include it more often than not. A dependency is any state, prop or context that is used within the useEffect callback, but you can also include state or props that are not.
• useEffect will trigger based on changes in the dependencies listed. ESLint will warn you if it expects a dependency, but one is not added, however, this is a warning and they are not required. === becomes === useEffect will trigger based on changes in the dependencies listed. ESLint will warn you if it expects a dependency, however, this is a warning and they are not required.

3. Additional Information: