update metrics on readme based on latest round of submissions

[carodew]

it should consider …

• supplanting the "outside SME" metric with "outside entities"
• any caveats or notes about changes that would affect the numbers
• clarifying the metric on setting up similar models at outside agencies and consulting engagements
• tweaking the number of submissions metric in the event that we move to a rolling submission period

it's done when …

• it's live on the GitHub repo readme.md and merged into master
• and another thing