docs: improvement to the Debian installation instructions (#4734)

* Slight improvement to the Debian installation instructions

I've managed to do an install on Debian Trixie with most of the required
dependencies from Debian, with the exception of Grafana (which is not)
packaged. As such, I've modified the instructions to reflect this.

It's possible that in the future, TeslaMate will require newer versions,
and these instructions would become outdated. But that's not worse than
the current state, where for example Erlang/Elixir are no longer
available upstream as documented, so better to have two sets of
instructions for redundancy.

* Improve the separate Grafana server explanation

* Rewrap the text

* Further improve the remot grafana URL

* docs: update changelog

---------

Co-authored-by: Jakob Lichterfeld <jakob-lichterfeld@gmx.de>

CHANGELOG.md

@@ -20,6 +20,8 @@
 
 #### Documentation
 
+- docs: improvement to the Debian installation instructions (#4734 - @iustin)
+
 ## [2.0.0] - 2025-04-26
 
 **This is a breaking change release:** TeslaMate uses PostgreSQL as database, this is an external dependency and needs to be updated by yourself. We now require PostgreSQL 16.7 or 17.3 or higher as we are upgrading the bundled earthdistance extension to v1.2. TeslaMate will now fail to start if you are using an older version. Ensure to upgrade your database before upgrading TeslaMate. To upgrade PostgreSQL, you need to follow these instructions:

website/docs/installation/debian.md

@@ -9,9 +9,13 @@ This document provides the necessary steps for installation of TeslaMate on a va
 
 Click on the following items to view detailed installation steps.
 
+Note that in very recent distributions, you might have the required versions already packaged. However, the contents or naming of the Debian/Ubuntu packages might slightly differ than the ones from upstream, so you might need to install extra packages or do other tweaks.
+
 <details>
   <summary>Postgres (v17.3+)</summary>
 
+Either upstream:
+
 ```bash
 wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
 echo "deb http://apt.postgresql.org/pub/repos/apt/ `lsb_release -cs`-pgdg main" | sudo tee /etc/apt/sources.list.d/pgdg.list
@@ -21,11 +25,19 @@ sudo apt-get install -y postgresql-17 postgresql-client-17
 
 Source: [postgresql.org/download](https://www.postgresql.org/download/)
 
+Or if you run a recent enough distribution (e.g. Debian Trixie:):
+
+```bash
+sudo apt install postgresql-17 postgresql-client-17
+```
+
 </details>
 
 <details>
   <summary>Elixir (v1.16+)</summary>
 
+Either from upstream:
+
 ```bash
 wget https://packages.erlang-solutions.com/erlang-solutions_2.0_all.deb && sudo dpkg -i erlang-solutions_2.0_all.deb
 sudo apt-get update
@@ -34,6 +46,12 @@ sudo apt-get install -y elixir esl-erlang
 
 Source: [erlang.org/downloads](https://www.erlang.org/downloads#prebuilt)
 
+Or if you run a recent enough distribution (e.g. Debian Trixie:):
+
+```bash
+sudo apt install erlang erlang-dev erlang-syntax-tools elixir
+```
+
 </details>
 
 <details>
@@ -69,6 +87,8 @@ Source: [mosquitto.org/download](https://mosquitto.org/download/)
 <details>
   <summary>Node.js (v20+)</summary>
 
+Either from upstream:
+
 ```bash
 curl -fsSL https://deb.nodesource.com/setup_20.x | sudo bash -
 sudo apt-get install -y nodejs
@@ -76,6 +96,12 @@ sudo apt-get install -y nodejs
 
 Source: [nodejs.org/en/download/package-manager](https://nodejs.org/en/download/package-manager/all#debian-and-ubuntu-based-linux-distributions)
 
+Or if you run a recent enough distribution (e.g. Debian Trixie:):
+
+```bash
+sudo apt install nodejs npm
+```
+
 </details>
 
 ## Clone TeslaMate git repository
@@ -258,7 +284,13 @@ screen -S teslamate -L -dm bash -c "cd /usr/src/teslamate; ./start.sh; exec sh"
    Version: 10
    ```
 
-3. [Manually import](https://grafana.com/docs/reference/export_import/#importing-a-dashboard) the dashboard [files](https://github.com/teslamate-org/teslamate/tree/main/grafana/dashboards) or use the `dashboards.sh` script:
+3. Install `jq`:
+
+   ```bash
+   sudo apt install jq
+   ```
+
+4. [Manually import](https://grafana.com/docs/reference/export_import/#importing-a-dashboard) the dashboard [files](https://github.com/teslamate-org/teslamate/tree/main/grafana/dashboards) or use the `dashboards.sh` script:
 
    ```bash
    $ ./grafana/dashboards.sh restore
@@ -293,3 +325,15 @@ screen -S teslamate -L -dm bash -c "cd /usr/src/teslamate; ./start.sh; exec sh"
    ```
 
    :::
+
+   :::tip
+   In case you use a Grafana installation that runs on a separate server (for
+   example, an already existing Grafana install), set the `URL` variable to
+   point to it (the default points to `http://localhost:3000`, use a full URL,
+   including protocol, host and port):
+
+   ```bash
+   URL=<your-grafana-instance-url> ./grafana/dashboards.sh restore
+   ```
+
+   :::