doc: correct wording in readme regarding PostgreSQL versions used in pgjdbc regression testing
doc: correct wording in readme regarding PostgreSQL versions used in pgjdbc regression testing

Actually, versions since 8.2 are tested, not 8.4 as was previously mentioned.

jamesthomp/pgjdbc,panchenko/pgjdbc,jamesthomp/pgjdbc,sehrope/pgjdbc,AlexElin/pgjdbc,whitingjr/pgjdbc,lordnelson/pgjdbc,zapov/pgjdbc,jkutner/pgjdbc,marschall/pgjdbc,davecramer/pgjdbc,zemian/pgjdbc,zemian/pgjdbc,sehrope/pgjdbc,jorsol/pgjdbc,marschall/pgjdbc,golovnin/pgjdbc,zapov/pgjdbc,marschall/pgjdbc,lordnelson/pgjdbc,whitingjr/pgjdbc,golovnin/pgjdbc,Gordiychuk/pgjdbc,AlexElin/pgjdbc,jamesthomp/pgjdbc,Gordiychuk/pgjdbc,panchenko/pgjdbc,zapov/pgjdbc,pgjdbc/pgjdbc,jorsol/pgjdbc,Gordiychuk/pgjdbc,marschall/pgjdbc,AlexElin/pgjdbc,pgjdbc/pgjdbc,zemian/pgjdbc,sehrope/pgjdbc,davecramer/pgjdbc,whitingjr/pgjdbc,jkutner/pgjdbc,jorsol/pgjdbc,davecramer/pgjdbc,pgjdbc/pgjdbc,pgjdbc/pgjdbc,jorsol/pgjdbc,jkutner/pgjdbc,davecramer/pgjdbc,golovnin/pgjdbc,lordnelson/pgjdbc,panchenko/pgjdbc,sehrope/pgjdbc