Feature summary (what you would like to be able to do and where):

Add the MOS and MOS talk namespaces to the filter namespace list.

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):

• Make a list of pages
• Click the "Filter" button
• Look at the namespace list

Benefits (why should this be implemented?):
The MOS namespace was recently added to en.wiki as a new namespace