Wp-calypso: People: Add clarification text about distinction Followers/Email Followers

[zdenys]

Steps to reproduce

1. Go to https://wordpress.com/people/followers or https://wordpress.com/people/email-followers/

What I expected

See a short clarification about who Followers an Email Followers are (for example from the My Followers support page):

• Followers: A list of people currently following your site.
• Email Followers: A list of people who are subscribed to your blog via email only. They may or may not have a WordPress.com account.

It can be tooltip, some text below the tab name or else, as long as it clarifies the distinction between the lists.

What happened instead

No clarification is provided and it may confuse users.

Screenshot / Video

_Link: https://cld.wthms.co/8ua32n_

Context / Source

confusion #concierge #user-report in 2417022-zen

[Aurorum]

PR in #36701, proposing the tooltip suggested. :)

[zdenys]

This is awesome! Thanks for looking into this so quickly.