Add hint on system locales and install locales-all in bsae image

CHANGELOG.rst

@@ -14,6 +14,8 @@ Fixed
 
 * The menu button used to be displayed twice on smaller screens.
 * The icons were loaded from external servers instead from local server.
+* Weekdays were not translated if system locales were missing
+  * Added locales-all to base image and note to docs
 
 Changed
 ~~~~~~~

Dockerfile

@@ -36,6 +36,7 @@ RUN apt-get -y update && \
         less \
 	libpq-dev \
 	libssl-dev \
+	locales-all \
 	postgresql-client-14 \
         pspg \
 	python3-dev \

docs/admin/10_install.rst

@@ -34,6 +34,7 @@ For an installation on a dedicated server, the following prerequisites are neede
  * nginx
  * Python 3.9
  * Some system dependencies to build Python modules and manage frontend files
+ * System locales for all supported languages
  * The aforementioned paths
 
 Install system packages
@@ -53,7 +54,8 @@ Install some packages from the Debian package system.
                python3-virtualenv \
                chromium \
                redis-server \
-               postgresql
+               postgresql \
+               locales-all
 
 Create PostgreSQL user and database
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~