docs: add release phases to support policy (#10091)

### Description

Documents our release phases.

Please check the feature lists for each phase for completeness/accuracy.

### Testing Instructions

👀

---------

Co-authored-by: Chris Olszewski <[email protected]>
Co-authored-by: Thomas Knickman <[email protected]>

Author: 3 people

docs/repo-docs/getting-started/support-policy.mdx

@@ -8,7 +8,7 @@ import { Callout } from '#/components/callout';
 ## Package managers
 
 Core `turbo` functionality depends on the package managers in the JavaScript ecosystem and their implementations of Workspaces and
-lockfiles formats.
+lockfile formats.
 
 | Package manager | Supported                       |
 | --------------- | ------------------------------- |
@@ -69,3 +69,52 @@ We highly encourage you to use the most current version of Turborepo whenever po
 | ------------- | ------------ | ---------------- |
 | 2.x           | Jun. 4, 2024 |                  |
 | 1.x           | Dec. 9, 2021 | Jun. 4, 2026     |
+
+## Release phases
+
+Stable builds of Turborepo follow semantic versioning (semver) and are thoroughly tested before being released.
+
+Turborepo also offers specific APIs that may be released in an earlier phase of development. This is to allow early adopters to give valuable feedback and help the core team gain confidence in APIs ahead of their stable release. APIs that are available pre-stable will be marked as such in the documentation and within `turbo` itself whenever possible.
+
+Not every API will be released in every phase. We use our best judgement to determine the phase for an API based on our confidence for the feature, weighing factors like the feature's complexity, possible use cases, and feedback from early users of the API.
+
+The Turborepo core team would like to thank any users who do use features early and express our appreciation for any feedback you provide.
+
+### Stable
+
+When an API reaches stability, it is considered ready for use in production. APIs marked as stable will only change in a backward-compatible way in a major release.
+
+- If a stable API is going to **have breaking changes** in an upcoming major release, warnings and documentation will be provided to help with migrations and next steps.
+- If a stable API is going to be **removed** in an upcoming major release, it will be marked as [Deprecated](#deprecated) to provide early notice of future removal.
+
+### Beta
+
+Beta APIs require more confidence around reliability before a stable release. In the Beta phase, we are confident about the overall design of the feature and expect to be able to promote the feature to stable with relatively few changes. In rare cases, an API may require a breaking change and will not be covered by semver.
+
+We encourage early adopters to use Beta APIs to help us gain certainty around the feature's design and stability. Depending on your risk tolerance, you can use the feature in production as you see fit.
+
+**APIs currently in the Beta phase:**
+
+- None
+
+### Experimental
+
+Experimental APIs lack essential capabilities required to be ready for stability. The design of the feature is considered to be under active development and can change at any time.
+
+We encourage you to help us test experimental APIs in side projects, proof-of-concepts, and other environments where stability is non-essential. This gives you the opportunity to aid in the API's development by providing early feedback to the core team as the feature develops. We do not recommend using experimental APIs where reliability is essential.
+
+**APIs currently in the Experimental phase:**
+
+- [`turbo query`](/repo/docs/reference/query)
+- [`turbo boundaries`](/repo/docs/reference/boundaries) and [Tags](/repo/docs/reference/boundaries#tags)
+- [`turbo ls`](/repo/docs/reference/ls)
+- [`--experimental-write-cache` for `turbo watch`](/repo/docs/reference/watch#caching)
+- [`--output=json` for `turbo ls --affected` flag](/repo/docs/reference/ls)
+
+### Deprecated
+
+Deprecated APIs are in the process of being removed. Any feature we intend to remove will include documentation for existing users with next steps and information on when to expect the feature to be removed.
+
+**APIs that are currently deprecated:**
+
+- `TURBO_REMOTE_ONLY` and `--remote-only`: Use [`TURBO_CACHE`](/repo/docs/reference/system-environment-variables) or [--cache](/repo/docs/reference/run#--cache-options)