Wrong header levels on BasicAuth refGuide page

See https://lucene.apache.org/solr/guide/7_4/basic-authentication-plugin.html#using-basic-auth-with-solrj and https://lucene.apache.org/solr/guide/7_4/basic-authentication-plugin.html#using-the-solr-control-script-with-basic-auth

Both of these should be 2nd level paragraphs, not third below "Editing Authentication Plugin Configuration" as today