docs: add old changelog to new changelog

CHANGELOG.md

@@ -14,3 +14,113 @@ See [Conventional Commits](Https://conventionalcommits.org) for commit guideline
 
 * Add(bring back) span and trace decorators
 
+
+# The below is before automated changelog management
+
+## [2.3.0]
+
+[2.3.0]: https://github.com/spandex-project/spandex/compare/v2.3.0...v2.2.0
+
+### Added
+- `Spandex.current_context/1` and `Spandex.Tracer.current_context/1` functions,
+  which get a `Spandex.SpanContext` struct based on the current context.
+- `Spandex.inject_context/3` and `Spandex.Tracer.inject_context/2` functions,
+  which inject a distributed tracing context into a list of HTTP headers.
+
+### Changed
+- The `Spandex.Adapter` behaviour now requires an `inject_context/3` callback,
+  which encodes a `Spandex.SpanContext` as HTTP headers for distributed
+  tracing.
+
+## [2.2.0]
+
+[2.2.0]: https://github.com/spandex-project/spandex/compare/v2.2.0...v2.1.0
+
+### Added
+- The `Spandex.Trace` struct now includes `priority` and `baggage` fields, to
+  support priority sampling of distributed traces and trace-level baggage,
+  respectively. More details about these concepts can be found in the
+  OpenTracing documentation.  An updated version of the `spandex_datadog`
+  library will enable support for this feature in terms of the
+  `Spandex.Adapter` and `Sender` APIs.
+
+### Changed
+- It is no longer required that you specify the `env` option. If not specified,
+  it will default to `nil`. This is useful, for example, for allowing the
+  Datadog trace collector configured default to be used.
+- The `Spandex.Adapter.distributed_context/2` callback now expects a
+  `SpanContext` struct to be returned, rather than a `Map`.
+- Similarly, the `Spandex.continue_trace` function now expects a `SpanContext`
+  struct rather than a separate `trace_id` and `span_id`.
+- The sender API now calls the `send_trace` function, passing in a
+  `Spandex.Trace` struct, rather than passing a list of `Spandex.Span` structs.
+  This means that you need to update the `spandex_datadog` to a compatible
+  version.
+
+### Deprecated
+- `Spandex.continue_trace/4` is deprecated in favor of
+  `Spandex.continue_trace/3`
+- Similarly, `Tracer.continue_trace/4` is deprecated in favor of
+  `Tracer.continue_trace/3`
+
+## [2.1.0]
+It is recommended to reread the README, to see the upgrade guide and understand the changes.
+
+[2.1.0]: https://github.com/spandex-project/spandex/compare/v2.1.0...v1.6.1
+
+### Added
+- Massive changes, including separating adapters into their own repositories
+
+### Changed
+- Many interface changes, specifically around return values
+
+### Removed
+- Adapters now exist in their own repositories
+
+## [1.6.1] - 2018-06-04
+
+[1.6.1]: https://github.com/spandex-project/spandex/compare/v1.6.1...v1.6.0
+
+### Added
+- `private` key, when updating spans, for non-inheriting meta
+
+## [1.6.0] - 2018-06-04
+
+[1.6.0]: https://github.com/spandex-project/spandex/compare/v1.6.0...v1.5.0
+
+### Added
+- Storage strategy behaviour
+
+### Changed
+- Centralize most storage logic, requiring only the most adapter specific behaviour to be defined by the adapter.
+
+## [1.5.0] - 2018-06-02
+### Changed
+- Interface for updating span metadata, and creating with metadata has been updated
+- Check documentation for examples
+
+[1.5.0]: https://github.com/olivierlacan/keep-a-changelog/compare/v1.5.0...v1.4.1
+
+## [1.4.1] - 2018-05-31
+### Changed
+- Resolved an issue with distributed trace header parsing
+
+[1.4.1]: https://github.com/olivierlacan/keep-a-changelog/compare/v1.4.0...v1.4.1
+
+## [1.4.0] - 2018-05-29
+### Added
+- The tracer pattern
+- Modernized configuration
+- More: Please read the readme again!
+
+[1.4.0]: https://github.com/olivierlacan/keep-a-changelog/compare/v1.3.4...v1.4.0
+
+## [1.3.4] - 2018-05-25
+### Added
+- Support distributed tracing via trace headers.
+- Added a changelog
+
+### Changed
+- No new changes
+
+[1.3.4]: https://github.com/olivierlacan/keep-a-changelog/compare/v1.3.3...v1.3.4