fix debian flow instructions (grafana#3852)

* fix debian flow instructions

* Update docs/sources/static/set-up/install-agent-linux.md

Co-authored-by: Mischa Thompson <mischabear@gmail.com>

---------

Co-authored-by: Mischa Thompson <mischabear@gmail.com>

docs/sources/flow/install/linux.md

@@ -19,9 +19,9 @@ Ubuntu), complete the following steps:
 1. Open a terminal and run the following command to install Grafana's package repository:
 
    ```shell
-   mkdir -p /etc/apt/keyrings/
-   wget -q -O - https://apt.grafana.com/gpg.key | gpg --dearmor > /etc/apt/keyrings/grafana.gpg
-   echo "deb [signed-by=/etc/apt/keyrings/grafana.gpg] https://apt.grafana.com stable main" | tee /etc/apt/sources.list.d/grafana.list
+    sudo mkdir -p /etc/apt/keyrings/
+    wget -q -O - https://apt.grafana.com/gpg.key | gpg --dearmor | sudo tee /etc/apt/keyrings/grafana.gpg > /dev/null
+    echo "deb [signed-by=/etc/apt/keyrings/grafana.gpg] https://apt.grafana.com stable main" | sudo tee /etc/apt/sources.list.d/grafana.list
    ```
 
 2. With the repository installed, update the list of available packages:

docs/sources/static/set-up/install-agent-linux.md

@@ -13,8 +13,8 @@ Install Grafana Agent and get it up and running on Linux.
 
 1.  If your distribution supports the signed-by option, open a terminal and enter:
 ```shell
-$ mkdir -p /etc/apt/keyrings/
-$ wget -q -O - https://apt.grafana.com/gpg.key | gpg --dearmor | sudo tee /etc/apt/keyrings/grafana.gpg
+$ sudo mkdir -p /etc/apt/keyrings/
+$ wget -q -O - https://apt.grafana.com/gpg.key | gpg --dearmor | sudo tee /etc/apt/keyrings/grafana.gpg > /dev/null
 $ echo "deb [signed-by=/etc/apt/keyrings/grafana.gpg] https://apt.grafana.com stable main" | sudo tee /etc/apt/sources.list.d/grafana.list
 ```
 Otherwise, with the deprecated apt-key command: