Removed Link from ## User Handbook Section

[jankimoradiya]

Removed "Visit the User Handbook" link from ##User Handbook Section.

Description

We have removed "Visit the User Handbook" link from User Handbook section. Reff. #12585.

[ntwb]

Via #12605:

Currently the "User Handbook" section in the Gutenberg Handbook 404's

https://wordpress.org/gutenberg/handbook/

https://wordpress.org/gutenberg/handbook/users/
"Oops! That page can’t be found."
"It looks like nothing was found at this location. Maybe try one of the links below or a search?"

Let's remove the link until work in #11252 has started adding some pages to HelpHub at https://wordpress.org/support/