README.rst: use try-finally to close connection in CRUD example
README.rst: use try-finally to close connection in CRUD example

methane/PyMySQL,pymysql/pymysql,NunoEdgarGub1/PyMySQL,wraziens/PyMySQL,lzedl/PyMySQL,DashaChuk/PyMySQL,MartinThoma/PyMySQL,lzedl/PyMySQL,jheld/PyMySQL,PyMySQL/PyMySQL,anson-tang/PyMySQL,Ting-y/PyMySQL,xjzhou/PyMySQL,xjzhou/PyMySQL,eibanez/PyMySQL,boneyao/PyMySQL,nju520/PyMySQL,yeyinzhu3211/PyMySQL,wraziens/PyMySQL,yeyinzhu3211/PyMySQL,eibanez/PyMySQL,modulexcite/PyMySQL