Update CONTRIBUTING.md

Author: ZykeDev

CONTRIBUTING.md

@@ -9,7 +9,7 @@ Please ensure your pull request adheres to the following guidelines:
 * Search open and closed PR's to avoid duplicate suggestions.
 * The PR should have a useful title. If more details are needed, write them down in the PR description.
 * Feel free to suggest color/style changes, but remember this repo is mostly for personal use and therefore follows my ([@ZykeDev](https://github.com/ZykeDev)) personal preferences.
-* Try to use the :root variables as much as possible. If you feel like a new var is needed/useful, add it at the end of the :root definition.
+* Try to use the :root variables as much as possible. If you believe a new var is needed/useful, add it at the end of the :root definition.
 * Use shorthand where possible. e.g. `margin: 10px 10px 5px;`
 * Use the `!important` property only when needed.