Removes sed from Dockerfile (#948)

They were needed before because they changed example config.php so make it workable.
Now we don't have it and running sed against main file just removes a lot of code
and forces data path for directory

Dockerfile

@@ -22,7 +22,5 @@ RUN docker-php-ext-install \
 WORKDIR /var/www/html
 
 COPY tinyfilemanager.php index.php
-RUN sed -i "s/\$root_path =.*;/\$root_path = \$_SERVER['DOCUMENT_ROOT'].'\/data';/g" index.php && \
-    sed -i "s/\$root_url = '';/\$root_url = 'data\/';/g" index.php
 
 CMD ["sh", "-c", "php -S 0.0.0.0:80"]