Complete 'Cost Analysis' Section

[jaimiebutton]

As part of our SWRS documentation for execs, we'll need to communicate the cost analysis of a new system and of keeping the current system.

Acceptance Criteria:

• [x] Roughly calculate the current cost of maintaining SWRS (#129)
• [x] Roughly calculate time spent over the past few years maintaining SWRS
• [x] Roughly calculate the cost of developing a new system
• [x] Write this out in paragraph form for the final documentation

[pbastia]

@hannavovk @jaimiebutton @nanyangpro this is ready for review in the document