docs: fix typo on homepage of developer docs (#7047)

dev-docs/src/components/Homepage/index.js

@@ -15,7 +15,7 @@ const FeatureList = [
     Svg: require("@site/static/img/undraw_blank_canvas.svg").default,
     description: (
       <>
-        Want to build your own app powered by Excalidraw by don't know where to
+        Want to build your own app powered by Excalidraw but don't know where to
         start?
       </>
     ),