…stogram translation

Mark the OTLP Exponential Histogram to Prometheus Native Histogram (standard
exponential schema) conversion section as Stable. Restructure the bullets to
mirror the Histograms section established in open-telemetry#5091, splitting the
NoRecordedValue handling into explicit true/false branches.

Fix the NoRecordedValue handling: the Native Histogram Count is a uint64 and
MUST be set to zero (not the Stale NaN value) on staleness, with
ZeroCount/PositiveSpans/PositiveDeltas/NegativeSpans/NegativeDeltas left
empty. Set the Native Histogram ResetHint to UNKNOWN since OpenTelemetry
does not carry an explicit reset flag. Add StartTimeUnixNano handling
consistent with the Histograms section, and note that fields not explicitly
referenced are left at their zero value. Relax the delta-temporality rule
from "MUST be dropped" to "MAY be aggregated to cumulative or MUST be
dropped", matching the (now Stable) Histograms section.

Fixes open-telemetry#4922

Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>

Mirror the detailed explanation added for the OpenTelemetry Histogram to
Prometheus NHCB conversion in open-telemetry#5091: split the sparse-layout conversion
into separate bullets covering which counts are converted, delta encoding,
span Offset/Length semantics, and a worked example. Provide an explicit
formula (`Offset + i + 1`) for mapping an Exponential Histogram bucket
array position to a Native Histogram bucket index, since the indexing
convention differs by one between the two formats.

Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>

Mirror the detailed explanation added for the OpenTelemetry Histogram to
Prometheus NHCB conversion in open-telemetry#5091: split the sparse-layout conversion
into separate bullets covering which counts are converted, delta encoding,
span Offset/Length semantics, and a worked example. Provide an explicit
formula (`Offset + i + 1`) for mapping an Exponential Histogram bucket
array position to a Native Histogram bucket index, since the indexing
convention differs by one between the two formats.

Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>

### Context

- Clarify that environment variable propagation carriers normalize
requested
  keys, carrier keys, and returned keys.

([open-telemetry#5102](open-telemetry#5102))
- Specify that environment variable propagation carriers only read and
return
  normalized environment variable names.

([open-telemetry#5144](open-telemetry#5144))
- Specify that an empty environment variable propagation name is
non-normalized
  and normalizes to `_`.

([open-telemetry#5163](open-telemetry#5163))

### Profiles

- Remove duplicate information from and extend Profiles documentation
(README.md, pprof.md).

([open-telemetry#4932](open-telemetry#4932))

### Entities

- Add specification for communicating entity information as structured
log events.

([open-telemetry#4836](open-telemetry#4836))

### Common

- Add an in-development [SDK
self-observability](specification/self-observability.md)
  section, referenced from the Tracing, Metrics, and Logs SDK specs.

([open-telemetry#5087](open-telemetry#5087))
- Clarify non-OTLP representation guidance for nested `AnyValue` values
in
  arrays and maps.

([open-telemetry#5053](open-telemetry#5053))
- Add in-development guidance recommending a JSON object as the string
  representation for an attribute in non-OTLP protocols.

([open-telemetry#5028](open-telemetry#5028))
- Add in-development guidance recommending a JSON object as the string
  representation for an attribute collection in non-OTLP protocols.

([open-telemetry#5110](open-telemetry#5110))

### Compatibility

- Deprecate OpenCensus compatibility requirements in the specification.

([open-telemetry#5138](open-telemetry#5138))
- Stabilize sections of Prometheus Metrics Exporter.
  - Clarify resource attributes configuration.

([open-telemetry#5084](open-telemetry#5084))
- Stabilize the conversion of OTLP Summaries into Prometheus Summaries.

([open-telemetry#5107](open-telemetry#5107))
  - Stabilize client libs section.

([open-telemetry#5106](open-telemetry#5106))
- Stabilize Prometheus Metrics Exporter default aggregation
configuration.

([open-telemetry#5113](open-telemetry#5113))
- Stabilize sections of Prometheus and OpenMetrics Compatibility.
- Stabilize OpenTelemetry Histogram to Prometheus Histogram
transformation.

([open-telemetry#5091](open-telemetry#5091))
- Add optional OpenTelemetry Histogram to Prometheus Native Histogram
with Custom Buckets transformation.

([open-telemetry#5091](open-telemetry#5091))

### SDK Configuration

- Add link to declarative config IdGenerator type

([open-telemetry#5133](open-telemetry#5133))

### OTEPs

- Context-scoped Attributes.

([open-telemetry#4931](open-telemetry#4931))

---------

Co-authored-by: Reiley Yang <reyang@microsoft.com>