preemptive cleanup of 'Upgrading' section for 5.2 (SOLR-7325, SOLR-7336, SOLR-4839 - merge r1676350)
preemptive cleanup of 'Upgrading' section for 5.2 (SOLR-7325, SOLR-7336, SOLR-4839 - merge r1676350)

git-svn-id: e799fff536a883f3c27ef733fe770373e8a19271@1676351 13f79535-47bb-0310-9956-ffa450edef68

PATRIC3/p3_solr,PATRIC3/p3_solr,PATRIC3/p3_solr,PATRIC3/p3_solr,PATRIC3/p3_solr,PATRIC3/p3_solr,PATRIC3/p3_solr