Update tarantool.io after implementing a new doc structure

[Epic] Merging CE and EE documentation: https://github.com/tarantool/doc/issues/3547

In a new docs structure, the Tarantool Enterprise Edition section is going to be removed. Topics for EE features, EE module docs, and API references will be moved to corresponding sections in main docs. This change will require some updates on the website:

• Remove the Enterprise Edition item from the documentation chooser in the docs portal (https://www.tarantool.io/en/doc/latest/).
• Remove the Enterprise Edition item from the Documentation chooser in the header (https://www.tarantool.io/), rename Community Edition to something else. For example, we can keep two items - Tarantool and Data Grid (the same for the Enterprise Edition doc item in the footer).
• Remove the Enterprise Edition item from the footer (https://www.tarantool.io/).
• Update the EE docs link in the Customer zone page to the CE docs link. Can be renamed: Enterprise documentation -> Tarantool documentation.

Start with the documentation portal, the website header and footer, and the Customer zone page linked in the issue. Trace how each documentation chooser and link is generated, then verify that Enterprise Edition entries are removed or renamed as specified and the Customer zone points to the CE documentation.