docs: add -L to remaining curl install commands

default.nix

@@ -14,7 +14,7 @@ if ! builtins ? nixVersion || builtins.compareVersions requiredVersion builtins.
     - If you installed Nix using the install script (https://nixos.org/nix/install),
       it is safe to upgrade by running it again:
 
-          curl https://nixos.org/nix/install | sh
+          curl -L https://nixos.org/nix/install | sh
 
     For more information, please see the NixOS release notes at
     https://nixos.org/nixos/manual or locally at

nixos/doc/manual/installation/installing-from-other-distro.xml

@@ -47,7 +47,7 @@
     Short version:
    </para>
 <screen>
-<prompt>$ </prompt>curl https://nixos.org/nix/install | sh
+<prompt>$ </prompt>curl -L https://nixos.org/nix/install | sh
 <prompt>$ </prompt>. $HOME/.nix-profile/etc/profile.d/nix.sh # …or open a fresh shell</screen>
    <para>
     More details in the

nixos/doc/manual/release-notes/rl-1903.xml

@@ -173,7 +173,7 @@
      <listitem>
       <para>
        For users of a daemon-less Nix installation on Linux or macOS, you can
-       upgrade Nix by running <command>curl https://nixos.org/nix/install |
+       upgrade Nix by running <command>curl -L https://nixos.org/nix/install |
        sh</command>, or prior to doing a channel update, running
        <command>nix-env -iA nix</command>.
       </para>