Update ZendServer product URL

[hammermaps]

Proposed changes

Correction of the product link to the Zend Server.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves an existing code/behavior)
• Deprecated third party dependency update
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ x ] Documentation/Typo/Resource update that does not involve any code modification

Agreement

I have read the CONTRIBUTING and CODING GUIDELINE docs