docs: fix minor grammar and spellings (#7039)

dev-docs/docs/@excalidraw/excalidraw/customizing-styles.mdx

@@ -1,6 +1,6 @@
 # Customizing Styles
 
-Excalidraw is using CSS variables to style certain components. To override them, you should set your own on the `.excalidraw` and `.excalidraw.theme--dark` (for dark mode variables) selectors.
+Excalidraw uses CSS variables to style certain components. To override them, you should set your own on the `.excalidraw` and `.excalidraw.theme--dark` (for dark mode variables) selectors.
 
 Make sure the selector has higher specificity, e.g. by prefixing it with your app's selector:
 

dev-docs/docs/@excalidraw/excalidraw/integration.mdx

@@ -34,7 +34,7 @@ function App() {
 
 Since _Excalidraw_ doesn't support server side rendering, you should render the component once the host is `mounted`.
 
-The following worfklow shows one way how to render Excalidraw on Next.js. We'll add more detailed and alternative Next.js examples, soon.
+The following workflow shows one way how to render Excalidraw on Next.js. We'll add more detailed and alternative Next.js examples, soon.
 
 ```jsx showLineNumbers
 import { useState, useEffect } from "react";

dev-docs/docs/introduction/contributing.mdx

@@ -15,7 +15,7 @@ In case you want to pick up something from the roadmap, comment on that issue an
 1. Run `yarn` to install dependencies
 1. Create a branch for your PR with `git checkout -b your-branch-name`
 
-> To keep `master` branch pointing to remote repository and make pull requests from branches on your fork. To do this, run:
+> To keep `master` branch pointing to remote repository and make pull requests from branches on your fork, run:
 >
 > ```bash
 > git remote add upstream https://github.com/excalidraw/excalidraw.git