Guidelines to prevent excessive logging is confusing

[alanwest]

From the trace spec:

opentelemetry-specification/specification/trace/sdk.md

Lines 415 to 417 in 094fe9f

	There SHOULD be a log emitted to indicate to the user that an attribute, event,
	or link was discarded due to such a limit. To prevent excessive logging, the log
	should not be emitted once per span, or per discarded attribute, event, or links.

What is this meant to communicate?

To prevent excessive logging, the log should not be emitted once per span, or per discarded attribute, event, or links.

I want to improve the wording here, though the following are possible interpretations:

1. Whenever something is dropped or truncated on a span we should only log this for a fraction of the occurrences - e.g. 1 in 10 occurrences.
2. For a given span, if multiple things are dropped or truncated only log at most once per span.
3. Something else?

Or is it even important that the spec be prescriptive here? Another option would be to move this to a supplementary guidelines doc like we have for metrics. We could make a general guidelines doc that suggests that care should be taken when logging potentially high-frequency errors/warnings from the SDK.

[tigrannajaryan]

@alanwest will you be able to make a PR for this?