Change RPM install warning to EAP6

Installing both EAP and JWS via RPM currently has a warning in the docs:

http://documentation-devel.engineering.redhat.com/site/documentation/en-US/Red_Hat_JBoss_Web_Server/3/html-single/Installation_Guide/index.html#sect-RPM_Installation

It was advised on the JWS PM list that JWS 3 and EAP 7 will be compatible, so the warning should be changed to specifically state that JWS 3 and EAP 6 aren't compatible for both to be installed on the same machine:

...
Library version conflicts occur when using RPM packages to install both JBoss Web Server 3 and JBoss EAP 6 on the same machine. To workaround the issue, you can install either JBoss Web Server 3 or JBoss EAP 6 using the RPM installation method, and the other using the ZIP installation method.
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