Some small language updates to the readme. (GoogleChrome#2057)

README.md

@@ -7,9 +7,6 @@ create, and solve on the web. It's meant to not only educate developers, but
 help them apply what they've learned to any site they work on, be it personal or
 business.
 
-Note: this repo contains the written content for web.dev. The client-side JS and
-server are not yet open source but we hope to share them soon! 🙇‍♂️
-
 ## Found a bug? 👷‍♀️
 
 Thanks for letting us know! Please [file an issue](https://github.com/GoogleChrome/web.dev/issues/new?assignees=&labels=bug&template=bug_report.md&title=) and a team member should reply shortly.
@@ -45,11 +42,6 @@ npm run dev
 Open `http://localhost:8080/` to see the site locally. Changes to assets will
 rebuild the site. Refresh to see your changes.
 
-👉 The preview server allows you to see how the content will look on the
-production site, but it's not a true staging server. For example, features like
-search and JS components may not work or be entirely broken on the local
-preview.
-
 ## Staging 🕺
 
 When you send in a pull request it will be automatically staged for you. Keep an