Remove redundant information from signals doc

[krivard]

When I was messing around with #1009 I noticed that it was still displaying "per 100 people" even though that text never appeared in the source. It turned out this text was coming from descriptions.raw.txt and descriptions.generated.json, which both get refreshed by npm start. These files are read by constants.ts, and from there, used everywhere. To prevent these files from forcing outdated information into the web visualizations, we should remove all redundant fields from each listing.

Link to signals description doc

[krivard]

I've completed a pass with suggest changes turned on. I've left "format" and "units" alone for now; we can adjust changes for #1009 in a separate effort. @sgratzl would you take a quick pass to see if the proposed changes are likely to cause anything to explode?