Add histogram bucket boundaries to metric semconv yaml files

[trask]

open-telemetry/opentelemetry-specification#3390 adds this text to the relevant metrics:

This metric SHOULD be specified with
ExplicitBucketBoundaries
of [ 0, 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10 ].

but ideally this would be specified in the metric yaml file and autogenerated into the markdown file.