nits: update comments for consistency

Top-level comments are now always `/** */` (instead of `//` or `/* */`).

Use a consistent tense: "logged by" instead of "logs".

Don't link source code where the atom is logged from: this link is
guaranteed to get out of date. The source code is easy to find with grep
or codesearch. Also, one of these comments is already wrong.

Above decisions are made by an approximate majority vote from the
existing comments.

Flag: EXEMPT METRICS
Test: N/A, reformatting comments only
Change-Id: Ied3ad38660b0ac489d9af893427d5c355ff73dae