Update Ubuntu and Debian instructions to use new repository

We now have a repository that only contains a single `default`
distribution, because the package is generic enough to works across all
recent Ubuntu and Debian releases.

The new repository includes old versions in the `Packages` index to
allow users to install old versions via `apt install crate=x.y.z`

It also contains ARM64 packages.

docs/install/debian-ubuntu.rst

@@ -23,29 +23,22 @@ the CrateDB package repository::
     sudo apt install --yes apt-transport-https apt-utils curl gnupg lsb-release
 
     # Import the public GPG key for verifying the package signatures.
-    curl -sS https://cdn.crate.io/downloads/deb/DEB-GPG-KEY-crate | sudo tee /etc/apt/trusted.gpg.d/cratedb.asc
+    curl -sS https://cdn.crate.io/downloads/debian/DEB-GPG-KEY-crate | \
+        sudo tee /etc/apt/trusted.gpg.d/cratedb.asc
 
-    # Compute CrateDB package repository location.
-    [[ $(lsb_release --id --short) = "Debian" ]] && repository="apt"
-    [[ $(lsb_release --id --short) = "Ubuntu" ]] && repository="deb"
-    distribution=$(lsb_release --codename --short)
-
-    # Register with the CrateDB package repository.
-    echo "deb [signed-by=/etc/apt/trusted.gpg.d/cratedb.asc arch=amd64] https://cdn.crate.io/downloads/${repository}/stable/ ${distribution} main" \
-        | sudo tee /etc/apt/sources.list.d/cratedb.list
+    # Add CrateDB repository to Apt
+    echo "deb https://cdn.crate.io/downloads/debian/stable/ default main" | \
+        sudo tee /etc/apt/sources.list.d/crate-stable.list
 
 .. NOTE::
 
-    CrateDB provides both *stable release* and *testing release* channels. To
-    use the testing channel, replace ``stable`` with ``testing`` in the command
-    line above. You can read more about the `release workflow`_.
-
-    The walkthrough is based on the ``sudo`` program. If it is not installed on
-    your machine, run ``apt update; apt install --yes sudo`` as a ``root`` user.
+    CrateDB provides two repositories. A *stable* and a *testing* repository. To use
+    the testing repository, replace ``stable`` with ``testing`` in the command
+    above. You can read more about our `release workflow`_.
 
 Now, update the package sources::
 
-    sudo apt update
+    sh$ sudo apt update
 
 You should see a success message. This indicates that the CrateDB package
 repository is correctly registered.
@@ -55,7 +48,15 @@ Install CrateDB
 
 With everything set up, you can install CrateDB::
 
-    sudo apt install crate
+    sh$ sudo apt install crate
+
+After the installation is finished, you can start the ``crate`` service::
+
+    sh$ sudo systemctl start crate
+
+Once the service is up and running, you can access CrateDB by visiting::
+
+    http://localhost:4200/
 
 
 .. include:: _control-linux.rst