Reorganize specification related to OTLP file exporter (#3031)

Fixes #3003 
Contributes to #2911

## Changes

This PR moves and reorganizes parts of the specification relevant to exporting OTLP data to a file.

* Removes the "Build-in exporters" section from the Log SDK. The OTLP exporter has its own specification covering all signals. The part regarding a file exporter is not unique to logs. Exporting OTLP data to a file is also applicable to trace and metric data.
* Moves the file describing OTLP JSON serialization under the `protocol` subdirectory. As discussed in the Logs SIG (12/7/2022), this file provides a foundation for further progress on specifying an OTLP file exporter.

specification/logs/data-model.md

@@ -476,7 +476,7 @@ If included, they MUST follow the OpenTelemetry
 ## Example Log Records
 
 For example log records see
-[JSON File serialization](../../experimental/serialization/json.md).
+[JSON File serialization](../protocol/file-exporter.md#examples).
 
 ## Appendix A. Example Mappings
 

specification/logs/sdk.md

@@ -27,9 +27,6 @@
     + [Export](#export)
     + [ForceFlush](#forceflush-2)
     + [Shutdown](#shutdown-1)
-  * [Built-in exporters](#built-in-exporters)
-    + [OTLP Exporter](#otlp-exporter)
-    + [OTLP File exporter](#otlp-file-exporter)
 
 <!-- tocstop -->
 
@@ -365,21 +362,3 @@ return a Failure result.
 `Shutdown` SHOULD NOT block indefinitely (e.g. if it attempts to flush the data
 and the destination is unavailable). [OpenTelemetry SDK](../overview.md#sdk)
 authors MAY decide if they want to make the shutdown timeout configurable.
-
-### Built-in exporters
-
-TODO: Break out into files under `./sdk_exporters`.
-
-#### OTLP Exporter
-
-Exports to an OTLP network destination via OTLP/gRPC or OTLP/HTTP.
-
-#### OTLP File exporter
-
-Writes to a file or stdout in either OTLP JSON or OTLP Protobuf binary format.
-
-![Logging to File](img/otlp-file.png)
-
-TODO: clarify how this functionality co-exists with the overlapping
-functionality in logging libraries that allow specifying how logs are written to
-a file.

experimental/serialization/json.md → specification/protocol/file-exporter.md

@@ -1,23 +1,25 @@
-# JSON File serialization
+# OpenTelemetry Protocol File Exporter
 
 **Status**: [Experimental](../../specification/document-status.md)
 
+This document provides a placeholder for specifying an OTLP exporter capable of
+exporting to either a file or stdout.
+
+Currently, it only describes the serialization of OpenTelemetry data to the OTLP JSON format.
+
 ## Table of Contents
 
-- [Overview](#overview)
-- [Requirements](#requirements)
+- [JSON File serialization](#json-file-serialization)
   - [File storage requirements](#file-storage-requirements)
     - [JSON lines file](#json-lines-file)
     - [Streaming appending](#streaming-appending)
   - [Telemetry data requirements](#telemetry-data-requirements)
-- [Examples](#examples)
+  - [Examples](#examples)
 
-## Overview
+## JSON File serialization
 
 This document describes the serialization of OpenTelemetry data as JSON objects that can be stored in files.
 
-## Requirements
-
 ### File storage requirements
 
 #### JSON lines file
@@ -33,7 +35,7 @@ This file is a JSON lines file (jsonlines.org), and therefore follows those requ
 
 There is no guarantee that the data in the file is ordered.
 
-There is no guarantee in particular that timestamps will be monotically increasing.
+There is no guarantee in particular that timestamps will be monotonically increasing.
 
 ### Telemetry data requirements
 
@@ -46,7 +48,7 @@ Only top-level objects, `ExportTraceServiceRequest`, `ExportMetricsServiceReques
 
 Files must contain exactly one type of data: traces, metrics, or logs.
 
-## Examples
+### Examples
 
 This is an example showing traces: