It appears that CA has moved the documentation, and in the process, has broken all of the links in their guides.
Dx NetOps Performance Management 3.7
Product has been re-branded to Dx NetOps Performance Management
To get tot he documentation:
1. Go to: https://techdocs.broadcom.com/
2. Click CA Enterprise Software
3. Click IT Operations Management
4. Click Dx NetOps Performance Management