new docs front page

[mashby2022]

Overview

We need to make changes to Botkube's docs front page to be more user-friendly and introduce a new section about AI assistant. Notion page.
Format should be similar to https://docs.testkube.io/
Specifically:
De-emphasize open-source focus: Revise the installation page to downplay open-source aspects and make cloud the default installation.
Add AI section: Create a dedicated AI section on the usage page(how it is pre-installed, how to disable it, generic image of what is/architecture, how to get started with 3-5 examples commands)

Acceptance Criteria

• Introduce "Home" Page, Dashboard which navigate user to the most important parts of the docs. This page also should bold the main features of Botkube.
• Update Installation Documentation: The revised installation page should reduce its emphasis on being open-source.
• Create AI Section in Usage Documentation: The usage page should include a new AI section with the elements described above.

Reason

Improved User Experience (Installation)
Enhanced Understanding of AI Assistant

[madebyrogal]

@miklosp we need your input here. Designs of the home page at least