Update link to Weld docs

There is a link to weld docs in EAP 7.1 Migration Guide:
Weld 2.3.3.Final - CDI Reference Implementation which leads to http://docs.jboss.org/weld/reference/latest/en-US/html_single/ - but it's for Weld 2.4.7.

The latest symlink in Weld docs is going to be changed to Weld 3 stream. Therefore I suggest updating the link to directly point to http://docs.jboss.org/weld/reference/2.4.7.Final/ which is included in EAP 7.1.4.

sgilda_jira, FYI as you are currently updating the same part in EAP 7.2 docs.