Documentation translation (#199)

Documentation translation using weblate.

* Use po4a to generate .po files from the english markdowns, then to generate translated files
* Some pages can be marked as «english only» (for technical documentation for example)
* New Hugo shortcode to use application strings in documentation (for example for settings names)
* The code of conduct is no more translated, but there is a link to official Contributor Covenant translations
* Adding all plugin's supported languages

Related to https://github.com/JohnXLivingston/peertube-plugin-livechat/issues/117

support/documentation/content/en/documentation/installation/_index.md

@@ -0,0 +1,18 @@
+---
+title: "Installation guide"
+description: "Plugin peertube-plugin-livechat installation guide"
+weight: 10
+chapter: false
+---
+
+{{% notice info %}}
+Before updating to a major release, please read the release notes and breaking changes list : [CHANGELOG](https://github.com/JohnXLivingston/peertube-plugin-livechat/blob/main/CHANGELOG.md).
+{{% /notice %}}
+
+{{% notice tip %}}
+To install or update the plugin, **just use the Peertube web admin interface**.
+{{% /notice %}}
+
+Here are some other more specific instructions:
+
+{{% children style="li" depth="3" description="true" %}}

support/documentation/content/en/documentation/installation/cpu_compatibility.md

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+---
+title: "Known issues: CPU Compatibility"
+description: "For now, the plugin only works out of the box for x86_64 and arm64 CPU architecture. Here are some instructions for other CPU architectures."
+weight: 10
+chapter: false
+---
+
+The Prosody AppImage included in the plugin will only work on x86_64 and arm64 CPU.
+It is not compatible with other CPU architectures.
+
+To use the plugin, you will have to manually install Prosody on your server
+(see below).
+
+Note: the plugin requires Prosody >= 0.12.0.
+If you are using an older version, Chat Federation could be broken, and it could have some unexpected behaviour.
+
+Once it is done, you have to check `Use system Prosody` in the plugin settings.
+
+## On non-docker Peertube installation
+
+For standard installation, you just have to install the official `prosody` package for your linux distribution.
+
+For example, on Debian/Ubuntu:
+
+```bash
+sudo apt install prosody
+```
+
+You can then disable the service that starts automatically when you install Prosody (the plugin will launch a Prosody process, there is no need for the service to run).
+For example, on Debian/Ubuntu (and other Systemd based linux distributions):
+
+```bash
+sudo systemctl disable prosody && sudo systemctl stop prosody
+```
+
+Warning: do not disable Prosody if it is used for another service on your server, like for example Jitsi.
+
+## Docker
+
+You will have to generate a Peertube image that includes Prosody in the same container that Peertube.
+I know this is not the standard way to do this with Docker, but keep in mind it is a temporary workaround.
+
+To generate and use such an image, please refer to the Docker documentation.
+The Docker file to generate the image should be:
+
+```Docker
+FROM chocobozzz/peertube:production-bullseye
+
+RUN apt -y update && apt install -y prosody && apt -y clean
+```
+
+## Yunohost
+
+You have to disable `metronome` (the XMPP server provided by Yunohost), and install `prosody`.
+
+This is already done by the Yunohost Peertube application, as it was required for the plugin before the v6.0.0.
+
+But it may be removed in a near feature (to avoid drawbacks of this method).
+I have to discuss with Yunohost team, to decide how we can do to minimize drawbacks, and maximize compatibility.

support/documentation/content/en/documentation/installation/upgrade_before_6.0.0.md

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+---
+title: "Upgrade from version older than 6.0.0"
+description: "Important notes when upgrading for an older version."
+weight: 50
+chapter: false
+---
+
+## IMPORTANT NOTE
+
+Since version v6.0.0, this plugin does not need any Prosody installation.
+
+If you were using this plugin before this version, and if you had installed Prosody manually, you can safely uninstall Prosody.
+
+If you were using the custom Peertube docker image that is embedding Prosody, you can switch back to the official Peertube image.