Kaveet Laxmidas

| Q | A | ---------------- | --- | Bug fix? | no | New feature? | no | Breaking change? | no | Deprecations? | no | Tests added?...

Clarify classification of metrics submitted via DogStatsD or Agent

1

### What does this PR do? Adds guidance for the treatment of metrics as Custom Metrics when using DogStatsD or Agent Checks. This language appears in /metrics/custom_metrics/ but is separately...

I was referencing the hosted docs when I noticed the incorrect spelling of the `txt` option for the `output` param. In the Swagger docs: ...