Warm Welcome: add the Search feature

[jeherve]

I think it would be nice to add Search to the list of features we promote in Warm Welcome:

cc @richardmuscat since you've worked on some readme changes lately.

[richardmuscat]

yup

[Viper007Bond]

I can take care of this if we get some copy and/or artwork for it.

[gibrown]

@Viper007Bond proposed copy changes:

In the first paragraph (

jetpack/_inc/client/components/welcome-new-plan/professional.jsx

Line 46 in 2f97004

{ __( 'Thanks for choosing Jetpack Professional. Jetpack is now backing up your content in real-time,' +

), change to:

Thanks for choosing Jetpack Professional. Jetpack is now backing up your content in real-time, indexing your content for search, scanning for security threats, and granting access to premium themes.

Add an extra paragraph after the themes paragraph (

jetpack/_inc/client/components/welcome-new-plan/professional.jsx

Line 51 in 2f97004

<p>

) of:

Give your visitor's a great search experience by letting them filter and sort fast, relevant search results.

Add a card prompting the user to "Add the Search (Jetpack) widget to your sidebar" in

jetpack/_inc/client/components/welcome-new-plan/professional.jsx

Line 89 in 2f97004

<Card