message: use a single run in the solr docker example.
diff: @@ -37,9 +37,9 @@ To implement multiple cores, you will also need to ship your own solr schema as
  FROM amazeeio/solr:6.6-drupal
  -RUN precreate-core drupal-index1 /solr-conf
  -RUN precreate-core drupal-index2 /solr-conf
  -RUN precreate-core drupal-index3 /solr-conf
  +RUN precreate-core drupal-index1 /solr-conf && \
  + precreate-core drupal-index2 /solr-conf && \
  + precreate-core drupal-index3 /solr-conf
  CMD ["solr-foreground"]
  