Adjust content for handheld devices

[renintw]

Since https://github.com/WordPress/wporg-gutenberg/pull/47, we have a layout for handheld devices. It still needs some adjustments for its content to be compatible with the handheld devices' semantics.

For example, we currently removed the text Click around to explore them, but we can ask for further feedback and see what's the best for it.	Mobile	Desktop