Improve FB employee version warning

Summary: Wording was a bit strange.

Reviewed By: passy

Differential Revision: D18063264

fbshipit-source-id: 29fb6f16ba6246f307d956a0309dbd153878a251

src/chrome/WarningEmployee.tsx

@@ -46,9 +46,8 @@ export default function WarningEmployee(props: {
     <Container>
       <Box>
         <Warning>
-          You are using the open-source version of Flipper. You will get access
-          to more plugins. To use the internal version, please install it from
-          Managed Software Center
+          You are using the open-source version of Flipper. Install the internal
+          build from Managed Software Center to get access to more plugins.
         </Warning>
         <AckButton onClick={props.onClick}>Okay</AckButton>
       </Box>