Removed mention of namespaces in first section of readme.
Removed mention of namespaces in first section of readme.

Namespaces weren't referenced in the section that the sentence was
refering to. For many using externals, namespaces are optional.

CIBC-Internal/cpm,iauns/cpm,SteffenL/cpm,iauns/cpm,CIBC-Internal/cpm,SteffenL/cpm