THEX v6.1 — upload instructions

1) Upload the file named `remote-install.sh` as:
   public_html/install

2) Create:
   public_html/release/

3) Upload:
   release/manifest.json
   release/thex-v6.1.tar.gz

4) Test in a browser:
   https://panel.thex.cam/install
   https://panel.thex.cam/release/manifest.json

5) On a fresh Ubuntu 22.04 VPS run:
   curl -fsSL https://panel.thex.cam/install | bash

Do not change the tar.gz after the manifest SHA-256 is generated.
