[editorial] Update SemConv v1.39 URLs and RPC metric names (#4838)

### Changes

References
#4838

#### `specification/compatibility/opencensus.md` 

* Updates the URL to match the semconv v1.39 anchors at
<https://opentelemetry.io/docs/specs/semconv/rpc/rpc-metrics/#metric-rpcservercallduration>.
* Updates the metric name `rpc.server.duration` ->
`rpc.server.call.duration`.
* This was previously updated in #4778 and subsequently rolled back in
#4790 to unbreak the build.

#### `specification/trace/api.md`

* Updates the URL for "Database Client Semantic Conventions" to match
new path at
<https://opentelemetry.io/docs/specs/semconv/db/database-spans/>.

---

/cc @lmolkova @chalin

---------

Signed-off-by: Vitor Vasconcellos <[email protected]>

Author: vitorvasc

specification/compatibility/opencensus.md

@@ -17,7 +17,7 @@ instrumented codebases.
 Migrating from OpenCensus to OpenTelemetry may require breaking changes to the telemetry produced
 because of:
 
-* Different or new semantic conventions for names and attributes (e.g. [`grpc.io/server/server_latency`](https://github.com/census-instrumentation/opencensus-specs/blob/master/stats/gRPC.md#server) vs [`rpc.server.duration`](https://opentelemetry.io/docs/specs/semconv/rpc/rpc-metrics/#metric-rpcserverduration))
+* Different or new semantic conventions for names and attributes (e.g. [`grpc.io/server/server_latency`](https://github.com/census-instrumentation/opencensus-specs/blob/master/stats/gRPC.md#server) vs [`rpc.server.call.duration`](https://opentelemetry.io/docs/specs/semconv/rpc/rpc-metrics/#metric-rpcservercallduration))
 * Data model differences (e.g. OpenCensus supports [SumOfSquaredDeviations](https://github.com/census-instrumentation/opencensus-proto/blob/v0.3.0/src/opencensus/proto/metrics/v1/metrics.proto#L195), OTLP does not)
 * Instrumentation API feature differences (e.g. OpenCensus supports [context-based attributes](https://github.com/census-instrumentation/opencensus-specs/blob/master/stats/Record.md#recording-stats)), OTel does not)
 * Differences between equivalent OC and OTel exporters (e.g. the OpenTelemetry Prometheus exporter [adds type and unit suffixes](prometheus_and_openmetrics.md#metric-metadata-1); OpenCensus [does not](https://github.com/census-ecosystem/opencensus-go-exporter-prometheus/blob/v0.4.1/prometheus.go#L227))

specification/trace/api.md

@@ -764,7 +764,7 @@ are built and instrumented.
 [Semantic conventions](../overview.md#semantic-conventions) for
 specific technologies should document kind for each span they define.
 
-For instance, [Database Client Semantic Conventions](https://opentelemetry.io/docs/specs/semconv/database/database-spans/)
+For instance, [Database Client Semantic Conventions](https://opentelemetry.io/docs/specs/semconv/db/database-spans/)
 recommend using `CLIENT` span kind to describes database calls.
 If the database client communicates to the server over HTTP, the HTTP
 instrumentation (when enabled) creates nested `CLIENT` spans to track individual