doc: upgrade/migration guide for SDK 2.0 (#5513)

Co-authored-by: Marc Pichler <[email protected]>
Co-authored-by: Jamie Danielson <[email protected]>

Author: 3 people

CHANGELOG.md

@@ -6,6 +6,7 @@ All notable changes to this project will be documented in this file.
 For API changes, see the [API CHANGELOG](api/CHANGELOG.md).
 For experimental package changes, see the [experimental CHANGELOG](experimental/CHANGELOG.md).
 For semantic convention package changes, see the [semconv CHANGELOG](packages/semantic-conventions/CHANGELOG.md).
+For notes on migrating to 2.x / 0.200.x see [the upgrade guide](doc/upgrade-to-2.x.md).
 
 ## Unreleased
 
@@ -52,7 +53,7 @@ For semantic convention package changes, see the [semconv CHANGELOG](packages/se
 * feat(core)!: remove deprecated samplers [#5316](https://github.com/open-telemetry/opentelemetry-js/pull/5316) @pichlermarc
   * (user-facing): deprecated `AlwaysOnSampler` has moved to `@opentelemetry/sdk-trace-base`
   * (user-facing): deprecated `AlwaysOffSampler` has moved to `@opentelemetry/sdk-trace-base`
-  * (user-facing): deprecated `TraceIdRatioSampler` has moved to `@opentelemetry/sdk-trace-base`
+  * (user-facing): deprecated `ParentBasedSampler` has moved to `@opentelemetry/sdk-trace-base`
   * (user-facing): deprecated `TraceIdRatioSampler` has moved to  `@opentelemetry/sdk-trace-base`
 * feat(resource): Merge sync and async resource interfaces into a single interface [#5350](https://github.com/open-telemetry/opentelemetry-js/pull/5350) @dyladan
   * Resource constructor now takes a single argument which contains an optional `attributes` object

README.md

@@ -373,7 +373,7 @@ These instrumentations are hosted at <https://github.com/open-telemetry/opentele
 
 ## Useful links
 
-- Upgrade guidelines: [Upgrade Guide](./doc/upgrade-guide.md)
+- [Upgrade to SDK 2.x guide](./doc/upgrade-to-2.x.md)
 - For more information on OpenTelemetry, visit: <https://opentelemetry.io/>
 - For help or feedback on this project, join us in [GitHub Discussions][discussions-url]