Highlight alternative Angular Material/CDK install

[cgrail]

I've just spent hours to find an issue with my first Angular Material app. I didn't read the first sentence of the first step and was just copy/pasting npm install commands. I got a lot of weird issues and couldn't get a simple app running. Eventually I figured out I made a mistake in the first step, but only after a few hours. As installing both modules can really screw up everything, I think that highlighting the choice might be a good idea.

[googlebot]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please visit https://cla.developers.google.com/ to sign.

Once you've signed, please reply here (e.g. I signed it!) and we'll verify. Thanks.

---

• If you've already signed a CLA, it's possible we don't have your GitHub username or you're using a different email address. Check your existing CLA data and verify that your email is set on your git commits.
• If your company signed a CLA, they designated a Point of Contact who decides which employees are authorized to participate. You may need to contact the Point of Contact for your company and ask to be added to the group of authorized contributors. If you don't know who your Point of Contact is, direct the project maintainer to go/cla#troubleshoot.
• In order to pass this check, please resolve this problem and have the pull request author add another comment and the bot will run again.

[cgrail]

I signed it

[googlebot]

CLAs look good, thanks!

[josephperrott]

LGTM

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}