Ref guide docs on select * are slightly misleading

Solr SQL does actually support select * type queries but only if the query includes a LIMIT clause, see: https://issues.apache.org/jira/browse/SOLR-8847

The ref guide claims Solr SQL does not support select * style queries. The intent of this JIRA is to clarify how this feature works for Solr 8.10 (where there are a number of SQL improvements included in that upcoming release).