Update VS Code Ext landing page text to specify to manually install Bicep Cli

We have the following Text and Link on the `details` page for the VSCode Bicep extension.
- That "Bicep VS Code Extension" link already points to the setup page
- https://learn.microsoft.com/en-us/azure/azure-resource-manager/bicep/install#vs-code-and-bicep-extension


We had some other issues where an Azure PowerShell user did not have the Bicep cli installed.

We document below that Bicep cli is a manual install in these circumstances.

#### Below are the scenarios that we want to cover for new users to point them to the right place and info to install Bicep cli:

---

### TODO: Update Text description on VS Code Landing page:
- Make **more prominent message and link** to the setup page, so that users should visit the docs page to learn how to manually install the Bicep Cli.

Start at the VS Code Bicep extension's details or landing page and review the existing "Bicep VS Code Extension" link to the documented setup page. Update the landing-page text so the setup link and the need to manually install the Bicep CLI are more prominent, then verify that the scenarios in the issue are clearly covered.

Written by the indexing model from the issue text.