Update Frequency Implementation

[shannonwells]

Problem

problem statement, including Closes: #219

Solution

Matched the patterns from Operations and Records and applied them to the Frequency Implementation Spec.

with @wilwade

Change summary:

• [x] Rewrote most of the existing Frequency Implementation Spec
• [x] Added Operations page
• [x] Added Records page

[wesbiggs]

Can you give it a readthrough for consistency in usage of () after method names? I think it's a bit of both at the moment, but not 100% sure.