Add required domain for VS Code Server installation to docs

[Kardi5]

When installing VS Code Server whitelisting the domain update.code.visualstudio.com is not enough as it redirects to vscode.download.prss.microsoft.com which also must be whitelisted.

Sample log for error:

wget https://update.code.visualstudio.com/commit:19e0f9e681ecb8e5c09d8784acaa601316ca4571/cli-alpine-x64/stable
--2025-05-09 13:41:16--  https://update.code.visualstudio.com/commit:19e0f9e681ecb8e5c09d8784acaa601316ca4571/cli-alpine-x64/stable
Resolving proxy-<REDACTED> (proxy-<REDACTED)... <REDACTED>
Connecting to proxy-<REDACTED> (proxy-<REDACTED>)|<REDACTED>|:8080... connected.
Proxy request sent, awaiting response... 302 Found
Location: https://vscode.download.prss.microsoft.com/dbazure/download/stable/19e0f9e681ecb8e5c09d8784acaa601316ca4571/vscode_cli_alpine_x64_cli.tar.gz [following]
--2025-05-09 13:41:16--  https://vscode.download.prss.microsoft.com/dbazure/download/stable/19e0f9e681ecb8e5c09d8784acaa601316ca4571/vscode_cli_alpine_x64_cli.tar.gz
Connecting to proxy-<REDACTED> (proxy-<REDACTED>)|<REDACTED>|:8080... connected.
Proxy tunneling failed: Forbidden
Unable to establish SSL connection.

[ntrogh]

@joaomoreno can you confirm that the vscode.download.prss.microsoft.com URL needs to be added for installing VS Code server on a remote machine?