docs: Update README to include chrome-emacs support

[KarimAziev]

This pull request updates the README to reflect the current state of browser extension support in Atomic Chrome for Emacs.

Given the removal of the Atomic Chrome extension from the Chrome Web Store, it's important for users to know about alternative ways to connect their browsers with Emacs. This update includes:

• Mentioning the support for the chrome-emacs extension, a fork of Atomic Chrome that is compatible with Manifest V3.
• Updating the installation instructions for Chrome users to include the option to install either GhostText or chrome-emacs.
• Clarifying in the "Select available browser extension" section that Atomic Chrome for Emacs now also accepts connection requests from chrome-emacs, and providing an example configuration for users who wish to use specific extensions.

These changes ensure that users have the most up-to-date information on how to integrate their browser with Emacs using Atomic Chrome and its supported extensions.