Add OTel logs source doc to doc website.

_data-prepper/pipelines/configuration/sources/otel-logs-source.md

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+---
+layout: default
+title: otel_logs_source 
+parent: Sources
+grand_parent: Pipelines
+nav_order: 25
+---
+
+# otel_logs_source
+
+
+The `otel_logs_source` source is an OpenTelemetry source that follows the [OpenTelemetry Protocol Specification](https://github.com/open-telemetry/oteps/blob/master/text/0035-opentelemetry-protocol.md), receives logs from the OTel Collector in the form of `ExportLogsServiceRequest` records.
+
+This source supports the `OTLP/gRPC` protocol.
+{: .note}
+
+## Configuration
+
+You can configure the `otel_logs_source` source with the following options. 
+
+| Option | Type | Description |
+| :--- | :--- | :--- |
+| port | int | Represents the port that the `otel_logs_source` is running on. Default value is `21892`. |
+| path | string | Represents the path for sending unframed HTTP requests. You can use this option to support unframed gRPC with HTTP idiomatic path to a configurable path. The path should start with `/` and length should be at least 1. `/opentelemetry.proto.collector.logs.v1.LogsService/Export` endpoint is disabled for both gRPC and HTTP requests if the path is configured. The path can contain `${pipelineName}` placeholder, which is replaced with pipeline name.  If the value is empty and `unframed_requests` is `true`, then the path that the source provides is `/opentelemetry.proto.collector.logs.v1.LogsService/Export`. | 
+| request_timeout | int | Represents the request timeout duration in milliseconds. Default value is `10000`. |
+| health_check_service | Boolean | Enables the gRPC health check service under `grpc.health.v1/Health/Check`. Default value is `false`. |
+| proto_reflection_service | Boolean | Enables a reflection service for Protobuf services (see [ProtoReflectionService](https://grpc.github.io/grpc-java/javadoc/io/grpc/protobuf/services/ProtoReflectionService.html) and [gRPC reflection](https://github.com/grpc/grpc-java/blob/master/documentation/server-reflection-tutorial.md) documents). Default value is `false`. |
+| unframed_requests | Boolean | Enables requests that are not framed using the gRPC wire protocol. Default value is `false`. |
+| thread_count  | int | The number of threads to keep in the `ScheduledThreadPool`. Default value is `500`. |
+| max_connection_count | int | The maximum number of open connections allowed. Default value is `500`. |
+
+### SSL
+
+You can configure SSL in the `otel_logs_source` source with the following options.
+
+| Option | Type | Description |
+| :--- | :--- | :--- |
+| ssl | Boolean | Enables TLS/SSL. Default value is `true`. |
+| sslKeyCertChainFile | string | Represents the SSL certificate chain file path or Amazon Simple Storage Service (Amazon S3) path. For example, see the Amazon S3 path `s3://<bucketName>/<path>`. Required if `ssl` is set to `true`.  |
+| sslKeyFile | string | Represents the SSL key file path or Amazon S3 path. For example, see the Amazon S3 path: `s3://<bucketName>/<path>`. Required if `ssl` is set to `true`.  |
+| useAcmCertForSSL | Boolean | Enables TLS/SSL using certificate and private key from AWS Certificate Manager (ACM). Default value is `false`. |
+| acmCertificateArn | string | Represents the ACM certificate ARN. ACM certificate take preference over Amazon S3 or local file system certificate.  Required if `useAcmCertForSSL` is set to `true`. |
+| awsRegion | string | Represents the AWS Region to use ACM or Amazon S3.  Required if `useAcmCertForSSL` is set to `true` or `sslKeyCertChainFile` and `sslKeyFile` is the Amazon S3 path. |
+
+## Usage
+
+To get started, create a `pipeline.yaml` file and add the `otel_logs_source` source as source:
+
+```
+source:
+    - otel_logs_source:
+```
+
+## Metrics
+
+You can use the following metrics with the `otel_logs_source`.
+
+| Option | Type | Description |
+| :--- | :--- | :--- | 
+| `requestTimeouts` | Counter | Measures the total number of requests that time out. | 
+| `requestsReceived` | Counter | Measures the total number of requests received by the `otel_logs_source`. |
+| `badRequests` | Counter | Measures the total number of requests that could not be parsed. |
+| `requestsTooLarge` | Counter | Measures the total number of requests that exceed the maximum allowed size. Indicates that the size of the data being written into the buffer is beyond the buffer's maximum capacity. |
+| `internalServerError` | Counter | Measures the total number of requests that are erroneous due to errors other than `requestTimeouts` or `requestsTooLarge`. |
+| `successRequests` | Counter | Measures the total number of requests successfully written to the buffer. |
+| `payloadSize` | Distribution summary | Measures the distribution of all incoming payload sizes. |
+| `requestProcessDuration` | Timer | Measures the duration of request processing. |