Merge pull request #2353 from wallabag/assets-fix

Basically, fix everything

docs/en/user/installation.rst

@@ -55,7 +55,7 @@ To install wallabag itself, you must run the following commands:
     git clone https://github.com/wallabag/wallabag.git
     cd wallabag
     git checkout 2.1.0
-    ASSETS=build ./install.sh
+    SYMFONY_ENV=prod composer install --no-dev -o --prefer-dist
     php bin/console wallabag:install --env=prod
 
 To start PHP's build-in server and test if everything did install correctly, you can do:

docs/en/user/upgrade-2.0.x-2.1.y.rst

@@ -15,7 +15,7 @@ The last release is published on https://www.wallabag.org/pages/download-wallaba
     git fetch origin
     git fetch --tags
     git checkout 2.1.0
-    ASSETS=build ./install.sh
+    SYMFONY_ENV=prod composer install --no-dev -o --prefer-dist
     php bin/console doctrine:migrations:migrate --env=prod
     php bin/console cache:clear --env=prod