Metrics: Update README to reflect recent changes.

The updates include:

- Mention the need for "Consent To Send Stats" to exists and the new
AreMetricsEnabled API.

- Replace wiki with XML references (need to add an internal only document
somewhere too).

- Reformat to take full advantage of 80-character lines.


Change-Id: Idbe06e70d5d15f1f8dbbb9475f38a1b0becbca32

Review URL:
1 file changed
tree: 843ee1068879b58eff8084f1a9db8899a4255570
  1. metrics/