Update README.md

zabbix_v2/Centos 6/agent2/README.md

 # scripts
 ### Instalação zabbix-agent2
 ```
-curl -fsSL https://git.usb.org.br/infra/zabbix/raw/master/zabbix_v2/Centos%207/agent2/zabbix_install.sh | bash -s -- <IP_PROXY> <SERVER_NAME>
+curl -fsSL https://git.usb.org.br/infra/zabbix/raw/master/zabbix_v2/Centos%206/agent2/zabbix_install.sh | bash -s -- <IP_PROXY> <SERVER_NAME>
 ```
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