[OpenAPI] Edits the autoscaling APIs

[lcawl]

This PR edits the text to align with https://www.elastic.co/guide/en/elasticsearch/reference/master/autoscaling-apis.html.
It also changes the examples from .json to .yaml files and adds them to the overlays.

Review notes

Since the openAPI document is too big for previews and not hooked into buildkite previews yet, if reviewers are wanting to review the strings, they all appear in the output/openapi/elasticsearch-openapi.json file.

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
autoscaling.delete_autoscaling_policy	⚪	Missing test	Missing test
autoscaling.get_autoscaling_capacity	⚪	Missing test	Missing test
autoscaling.get_autoscaling_policy	⚪	Missing test	Missing test
autoscaling.put_autoscaling_policy	⚪	Missing test	Missing test

You can validate these APIs yourself by using the make validate target.

[leemthompo]

Blind faith review! But I think I found one typo :)

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
autoscaling.delete_autoscaling_policy	⚪	Missing test	Missing test
autoscaling.get_autoscaling_capacity	⚪	Missing test	Missing test
autoscaling.get_autoscaling_policy	⚪	Missing test	Missing test
autoscaling.put_autoscaling_policy	⚪	Missing test	Missing test

You can validate these APIs yourself by using the make validate target.

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
autoscaling.delete_autoscaling_policy	⚪	Missing test	Missing test
autoscaling.get_autoscaling_capacity	⚪	Missing test	Missing test
autoscaling.get_autoscaling_policy	⚪	Missing test	Missing test
autoscaling.put_autoscaling_policy	⚪	Missing test	Missing test

You can validate these APIs yourself by using the make validate target.

[github-actions]

The backport to 8.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-8.x 8.x
# Navigate to the new working tree
cd .worktrees/backport-8.x
# Create a new branch
git switch --create backport-3081-to-8.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 b0860fca5b1e7049848d622b31481ff5f02a1a47
# Push it to GitHub
git push --set-upstream origin backport-3081-to-8.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-8.x

Then, create a pull request where the base branch is 8.x and the compare/head branch is backport-3081-to-8.x.

[github-actions]

The backport to 8.16 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-8.16 8.16
# Navigate to the new working tree
cd .worktrees/backport-8.16
# Create a new branch
git switch --create backport-3081-to-8.16
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 b0860fca5b1e7049848d622b31481ff5f02a1a47
# Push it to GitHub
git push --set-upstream origin backport-3081-to-8.16
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-8.16

Then, create a pull request where the base branch is 8.16 and the compare/head branch is backport-3081-to-8.16.