avatar_settings help text may not be accurate if avatar_defaults is filtered

[johnjamesjacoby]

The string says:

For users without a custom avatar of their own, you can either display a generic logo or a generated one based on their email address.

But, I have a need to remove generated Gravatars entirely using the avatar_defaults filter, which makes this text misleading.

In addition, this text is not wrapped in any defining HTML, making it impossible to reliably target with CSS or JS even.

[johnjamesjacoby]

Add filters for avatar types, plus 1 for the avatar help text (since several old plugins with many active installations modify this area)

[johnjamesjacoby]

Example with generated avatars removed