fixed pbm var env name in env docker

srcs/requirements/wordpress/Dockerfile

@@ -19,12 +19,13 @@ COPY ./conf/www.conf /etc/php7/php-fpm.d/
 RUN mkdir /run/php/
 
 ARG WP_VOLUME_DIR
+ARG WP_VOLUME_PLUGINS
 ARG MAX_UPLOAD_SIZE
 ARG EXECUTION_TIME
 
-# create and empty volume dir
-RUN mkdir -p ${WP_VOLUME_DIR} && \
-	rm -rf ${WP_VOLUME_DIR}/*
+# create and empty volumes dir
+RUN mkdir -p ${WP_VOLUME_DIR}   ${WP_VOLUME_PLUGINS} && \
+	rm -rf   ${WP_VOLUME_DIR}/* ${WP_VOLUME_PLUGINS}/*
 
 # replace max file size upload and execution time
 RUN sed -i "s/\(upload_max_filesize = \).*\(M\)/\1${MAX_UPLOAD_SIZE}\2/g" /etc/php7/php.ini && \