message: Add internal fields
diff: 1. Create an Application Insights resource in Azure by following [these instructions](https://docs.microsoft.com/en-us/azure/application-insights/app-insights-javascript?toc=/azure/azure-monitor/toc.json).
  2. Grab the _Instrumentation Key_ (aka "ikey") from the resource you created in
  step 1. Later, you'll add it .
  -3. Add Application Insights to your app via NPM or by [pasting a script snippet at the beginning of every `<head>` tag of each of your pages.](#snippet)
  +3. Add Application Insights to your app via NPM or by [pasting a script snippet at the beginning of every `<head>` tag of each of your pages.](#snippet-setup-(ignore-if-using-npm))
  ```sh
  npm i --save @microsoft/applicationinsights-web
  ```
  @@ -88,6 +88,7 @@ All autocollection is on by default. By using the full version of the JavaScript
  - Correlation context (if any) where request is made
  ### Telemetry Initializers
  +TODO
  ## Configuration
  Most configuration fields are named such that they can be defaulted to falsey.
  @@ -102,9 +103,9 @@ Most configuration fields are named such that they can be defaulted to falsey.
  | enableDebug | false | If true, internal debugging data is thrown as an exception by the logger. Default is false. |
  | disableExceptionTracking | false | If true, exceptions are no autocollected. Default is false. |
  | disableTelemetry | false | If true, telemetry is not collected or sent. Default is false. |
  -| consoleLoggingLevel | 0 | |
  -| telemetryLoggingLevel | 1 | |
  -| diagnosticLogInterval | false | |
  +| consoleLoggingLevel | 0 | (internal) Logs internal Application Insights errors to console. 0: off, 1: Critical errors only, 2: Everything (errors & warnings) |
  +| telemetryLoggingLevel | 1 | (internal) Sends internal Application Insights errors as telemetry. 0: off, 1: Critical errors only, 2: Everything (errors & warnings) |
  +| diagnosticLogInterval | false | (internal) Polling interval (in ms) for internal logging queue |
  | samplingPercentage | 100 | Percentage of events that will be sent. Default is 100, meaning all events are sent. Set this if you wish to preserve your datacap for large-scale applications. |
  | autoTrackPageVisitTime | false | |
  | disableAjaxTracking | false | If true, Ajax calls are not autocollected. Default is false. |
  