Jetpack: Improve styles on WPCOMScanUpsell +added WhatIsJetpack

[cleacos]

Changes proposed in this Pull Request

Improve some styles on WPCOMScanUpsell component and add to the bottom WhatIsJetpack component.

Before:

After:

Testing instructions

• Apply these changes and active Jetpack section with ?flags=jetpack/features-section
• Select AT site without Jetpack
• Go to Scan section and see the new What is Jetpack block and the styles applied like the screenshot

[matticbot]

Test live: https://calypso.live/?branch=update/jetpack-scan-wpcom-upsell

[matticbot]

Here is how your PR affects size of JS and CSS bundles shipped to the user's browser:

Sections (~228 bytes added 📈 [gzipped])

name  parsed_size           gzip_size
scan       +936 B  (+0.3%)     +228 B  (+0.3%)

Sections contain code specific for a given set of routes. Is downloaded and parsed only when a particular route is navigated to.

Legend

What is parsed and gzip size?

Parsed Size: Uncompressed size of the JS and CSS files. This much code needs to be parsed and stored in memory.
Gzip Size: Compressed size of the JS and CSS files. This much data needs to be downloaded over network.

Generated by performance advisor bot at iscalypsofastyet.com.

[ChaosExAnima]

Looks good!

[a8ci18n]

This Pull Request is now available for translation here: https://translate.wordpress.com/deliverables/3849798

Thank you @cleacos for including a screenshot in the description! This is really helpful for our translators.

[a8ci18n]

Translation for this Pull Request has now been finished.