*Breaking change* Deprecate CurvedAnimation.reverseCurve in favor of AsymmetricCurvedAnimation

[adil192]

Description of what this PR is changing or adding, and why:

Adds a migration guide for a breaking change in flutter/flutter#185797.

PRs or commits this PR depends on (if any):

• Deprecate CurvedAnimation.reverseCurve for AsymmetricCurvedAnimation flutter#185797

Presubmit checklist

• If you are unwilling, or unable, to sign the CLA, even for a tiny, one-word PR, please file an issue instead of a PR.
• If this PR is not meant to land until a future stable release, mark it as draft with an explanation.
• This PR follows the Google Developer Documentation Style Guidelines—for example, it doesn't use i.e. or e.g., and it avoids I and we (first-person pronouns).
• This PR uses semantic line breaks
  of 80 characters or fewer.

[sfshaza2]

/gcbrun

[flutter-website-bot]

Visit the preview URL for this PR (updated for commit 2321bc7):

https://flutter-docs-prod--pr13347-breaking-changes-deprecate-ftgcwv6g.web.app

[sfshaza2]

@adil192, can we land this? If so, please remove from draft model.

[adil192]

@sfshaza2 Don't we need to wait until flutter/flutter#185797 lands?

@loic-sharma Do we have a deprecation window to put in the Timeline section?

[gemini-code-assist]

Code Review

This pull request adds documentation for the deprecation of CurvedAnimation.reverseCurve in favor of AsymmetricCurvedAnimation and registers this new breaking change in the index. The review feedback focuses on correcting several API documentation link references where links meant for CurvedAnimation (such as reverseCurve and dispose) incorrectly point to AsymmetricCurvedAnimation. It also addresses a line length limit violation and suggests adding the missing reference link definitions.

[gemini-code-assist]

The link [reverseCurve][] currently points to AsymmetricCurvedAnimation/reverseCurve.html. Since this sentence refers to the deprecated field on CurvedAnimation, it should point to CurvedAnimation/reverseCurve.html instead. We can define a specific reference link [CurvedAnimation.reverseCurve] at the bottom of the file and use it here.

Suggested change

	[`CurvedAnimation`][]'s [`reverseCurve`][] field has been deprecated.
	[`CurvedAnimation`][]'s [`reverseCurve`][CurvedAnimation.reverseCurve] field has been deprecated.

[gemini-code-assist]

The link [reverseCurve][] here refers to the functionality of CurvedAnimation, so it should point to CurvedAnimation/reverseCurve.html instead of AsymmetricCurvedAnimation/reverseCurve.html.

Suggested change

	To support its [`reverseCurve`][] functionality,
	To support its [`reverseCurve`][CurvedAnimation.reverseCurve] functionality,

[gemini-code-assist]

This line exceeds the 80-character limit for semantic line breaks (it is 114 characters long). Additionally, the first [dispose][] link refers to calling dispose on CurvedAnimation, so it should point to CurvedAnimation/dispose.html instead of AsymmetricCurvedAnimation/dispose.html.

Let's wrap the text to adhere to semantic line breaks and use the correct link reference.

Suggested change

	Until the deprecation period is over, you must continue to
	call [`dispose`][] on [`CurvedAnimation`]. If you switch to [`AsymmetricCurvedAnimation`][], you must always call its
	[`dispose`][] method to clean up its active direction listeners.
	Until the deprecation period is over, you must continue to
	call [`dispose`][CurvedAnimation.dispose] on [`CurvedAnimation`].
	If you switch to [`AsymmetricCurvedAnimation`][],
	you must always call its [`dispose`][] method
	to clean up its active direction listeners.

[gemini-code-assist]

The link [reverseCurve][] here refers to CurvedAnimation's field, so it should point to CurvedAnimation/reverseCurve.html.

Suggested change

	If you need [`CurvedAnimation`][]'s [`reverseCurve`][] field,
	If you need [`CurvedAnimation`][]'s [`reverseCurve`][CurvedAnimation.reverseCurve] field,

[gemini-code-assist]

Add the new reference link definitions for CurvedAnimation.dispose and CurvedAnimation.reverseCurve to ensure the links resolve correctly.

Suggested change

	[`dispose`]: {{site.main-api}}/flutter/animation/AsymmetricCurvedAnimation/dispose.html
	[`parent`]: {{site.main-api}}/flutter/animation/CurvedAnimation/parent.html
	[`reverseCurve`]: {{site.main-api}}/flutter/animation/AsymmetricCurvedAnimation/reverseCurve.html
	[CurvedAnimation.dispose]: {{site.main-api}}/flutter/animation/CurvedAnimation/dispose.html
	[CurvedAnimation.reverseCurve]: {{site.main-api}}/flutter/animation/CurvedAnimation/reverseCurve.html
	[`dispose`]: {{site.main-api}}/flutter/animation/AsymmetricCurvedAnimation/dispose.html
	[`parent`]: {{site.main-api}}/flutter/animation/CurvedAnimation/parent.html
	[`reverseCurve`]: {{site.main-api}}/flutter/animation/AsymmetricCurvedAnimation/reverseCurve.html

[flutter-website-bot]

Staged preview of the updated docs.flutter.dev site (updated for commit ce8adfe):

https://flutter-docs-prod--docs-pr13347-breaking-changes-depre-s7gn3urm.web.app