This change removes references to "Hotfixes to the stable channel"

### Context

Hotfixes-to-the-stable-channel previously lived in the Flutter Wiki. The
decision was made to migrate the wiki to docs which opened an
opportunity to align with Dart on how we post our changelog.

flutter/flutter#151931 was merged to align the
processes by moving Hotfixes-to-the-stable-channel to the root of
Flutter and renaming it CHANGELOG.md to align with Dart.

Some missed links outside of flutter/flutter were called out in
flutter/flutter#152162.

**TLDR:** Move the changelog, currently called ["hotfixes to the stable
channel"](https://github.com/flutter/flutter/blob/master/docs/releases/Hotfixes-to-the-Stable-Channel.md),
to the root directory of Flutter/Flutter and rename it to CHANGELOG.md
before the Q3 release cutoff.

This PR accomplishes the following:
1. Renames 'Hotfixes-to-the-stable-channel' to CHANGELOG.md
2. Moves CHANGELOG.md to Flutter/Flutter root.
3. Update references to 'Hotfixes-to-the-stable-channel' to
CHANGELOG.md.

---

#### Background
Flutter has historically kept documentation on wiki pages in the Flutter
repository. Recently, we executed a large-scale migration of our wiki
into a `docs` folder within flutter/flutter.

#### Proposal
I propose relocating the current changelog, which is called ["hotfixes
to the stable
channel"](https://github.com/flutter/flutter/blob/master/docs/releases/Hotfixes-to-the-Stable-Channel.md),
to the root directory of the Flutter/Flutter repository and renaming it
to CHANGELOG.md. This change aims to improve the visibility,
accessibility, and consistency of our documentation processes.

#### Benefits
1. **Unify Dart and Flutter Processes:** This move aligns Flutter’s
changelog management with Dart's practices. As the release manager for
both Dart and Flutter, this unification will streamline the processes
and ensure consistency across projects.

#### Timeline
I would like this proposal **approved or denied before the Q3 release
cutoff** so it may be available within the stable branch.

---

> [!NOTE] 
> This proposal aims to improve our workflow and documentation
standards. I am open to feedback and further discussion on how we can
best implement this change.

# Flutter stable 3.24.0 Framework

## Scheduled Cherrypicks
- #151931

**TLDR:** Move the changelog, currently called ["hotfixes to the stable
channel"](https://github.com/flutter/flutter/blob/master/docs/releases/Hotfixes-to-the-Stable-Channel.md),
to the root directory of Flutter/Flutter and rename it to CHANGELOG.md
before the Q3 release cutoff.

This PR accomplishes the following:
1. Renames 'Hotfixes-to-the-stable-channel' to CHANGELOG.md
2. Moves CHANGELOG.md to Flutter/Flutter root.
3. Update references to 'Hotfixes-to-the-stable-channel' to
CHANGELOG.md.

---

#### Background
Flutter has historically kept documentation on wiki pages in the Flutter
repository. Recently, we executed a large-scale migration of our wiki
into a `docs` folder within flutter/flutter.

#### Proposal
I propose relocating the current changelog, which is called ["hotfixes
to the stable
channel"](https://github.com/flutter/flutter/blob/master/docs/releases/Hotfixes-to-the-Stable-Channel.md),
to the root directory of the Flutter/Flutter repository and renaming it
to CHANGELOG.md. This change aims to improve the visibility,
accessibility, and consistency of our documentation processes.

#### Benefits
1. **Unify Dart and Flutter Processes:** This move aligns Flutter’s
changelog management with Dart's practices. As the release manager for
both Dart and Flutter, this unification will streamline the processes
and ensure consistency across projects.

#### Timeline
I would like this proposal **approved or denied before the Q3 release
cutoff** so it may be available within the stable branch.

---

> [!NOTE] 
> This proposal aims to improve our workflow and documentation
standards. I am open to feedback and further discussion on how we can
best implement this change.

**TLDR:** Move the changelog, currently called ["hotfixes to the stable
channel"](https://github.com/flutter/flutter/blob/master/docs/releases/Hotfixes-to-the-Stable-Channel.md),
to the root directory of Flutter/Flutter and rename it to CHANGELOG.md
before the Q3 release cutoff.

This PR accomplishes the following:
1. Renames 'Hotfixes-to-the-stable-channel' to CHANGELOG.md
2. Moves CHANGELOG.md to Flutter/Flutter root.
3. Update references to 'Hotfixes-to-the-stable-channel' to
CHANGELOG.md.

---

#### Background
Flutter has historically kept documentation on wiki pages in the Flutter
repository. Recently, we executed a large-scale migration of our wiki
into a `docs` folder within flutter/flutter.

#### Proposal
I propose relocating the current changelog, which is called ["hotfixes
to the stable
channel"](https://github.com/flutter/flutter/blob/master/docs/releases/Hotfixes-to-the-Stable-Channel.md),
to the root directory of the Flutter/Flutter repository and renaming it
to CHANGELOG.md. This change aims to improve the visibility,
accessibility, and consistency of our documentation processes.

#### Benefits
1. **Unify Dart and Flutter Processes:** This move aligns Flutter’s
changelog management with Dart's practices. As the release manager for
both Dart and Flutter, this unification will streamline the processes
and ensure consistency across projects.

#### Timeline
I would like this proposal **approved or denied before the Q3 release
cutoff** so it may be available within the stable branch.

---

> [!NOTE] 
> This proposal aims to improve our workflow and documentation
standards. I am open to feedback and further discussion on how we can
best implement this change.