[MAINTAINER DOC] Define and document a deprecation process

DEPRECATED.md

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+# Deprecated
+
+This document lists all the items currently deprecated in opentelemetry-cpp.
+
+Deprecated items will be removed in the future.
+
+## Guidelines
+
+### Maintainer guidelines
+
+See the [deprecation-process](./docs/deprecation-process.md)
+
+## [TEMPLATE]
+
+### New Deprecation Title (Template)
+
+#### Announcement (Template)
+
+#### Motivation (Template)
+
+#### Scope (Template)
+
+#### Mitigation (Template)
+
+#### Planned removal (Template)
+
+## [Platforms]
+
+N/A
+
+## [Compilers]
+
+N/A
+
+## [Third party dependencies]
+
+### Jaeger
+
+See [Jaeger exporter](#jaeger-exporter)
+
+## [Build tools]
+
+N/A
+
+## [Build scripts]
+
+N/A
+
+## [opentelemetry-cpp API]
+
+N/A
+
+## [opentelemetry-cpp SDK]
+
+N/A
+
+## [opentelemetry-cpp Exporter]
+
+### Jaeger exporter
+
+#### Announcement (Jaeger)
+
+* Version: TO-BE-RELEASED-VERSION
+* Date: TO-BE-RELEASED-DATE
+* PR: [DEPRECATION] Deprecate the Jaeger exporter
+  [#9999](https://github.com/open-telemetry/opentelemetry-cpp/pull/9999)
+
+#### Motivation (Jaeger)
+
+The jaeger client libraries are deprecated, as announced
+[here](https://www.jaegertracing.io/docs/1.41/client-libraries/).
+
+The initial jaeger announcement in release 1.35 reads as:
+
+"
+We plan to continue accepting pull requests and making new releases of
+Jaeger clients through the end of 2021. In January 2022 we will enter a code
+freeze period for 6 months, during which time we will no longer accept pull
+requests with new features, with the exception of security-related fixes.
+After that we will archive the client library repositories and will no
+longer accept new changes.
+"
+
+At time of writing, Jan 2023, the client libraries have been archived 6
+months ago already.
+
+#### Scope (Jaeger)
+
+The following are deprecated and planned for removal:
+
+* all the code located under `exporters/jaeger/`, including:
+  * the jaeger exporter C++ class (`JaegerExporter`)
+  * the related factory (`JaegerExporterFactory`)
+  * the related options (`JaegerExporterOptions`)
+* the jaeger exporter library(`opentelemetry_exporter_jaeger_trace`)
+* the jaeger build options in CMake (`WITH_JAEGER`)
+* the dependency on thrift
+
+#### Mitigation (Jaeger)
+
+Jaeger supports natively the OTLP protocol, starting with jaeger 1.35.
+
+An application instrumented with opentelemetry needs to change how the SDK
+and exporter are configured to replace the Jaeger exporter with the OTLP
+exporter (both OTLP HTTP and OTLP GRPC are supported).
+
+#### Planned removal (Jaeger)
+
+* Date: After April 1st, 2023
+
+## [Documentation]
+
+N/A