Add task examples

[lcawl]

Relates to #2482

This PR adds more examples derived from https://www.elastic.co/guide/en/elasticsearch/reference/master/tasks.html and edits the descriptions.

[github-actions]

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

API	Status	Request	Response
tasks.cancel	🟢	2/2	2/2
tasks.get	🟢	10/10	10/10
tasks.list	🟢	9/9	9/9

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
tasks.cancel	🟢	2/2	2/2
tasks.get	🟢	10/10	10/10
tasks.list	🟢	9/9	9/9

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

[github-actions]

The backport to 8.17 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-8.17 8.17
# Navigate to the new working tree
cd .worktrees/backport-8.17
# Create a new branch
git switch --create backport-3509-to-8.17
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 4d7c5a293151660df6ba363dbbfb43f673fdc5b5
# Push it to GitHub
git push --set-upstream origin backport-3509-to-8.17
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-8.17

Then, create a pull request where the base branch is 8.17 and the compare/head branch is backport-3509-to-8.17.

[lcawl]

💚 All backports created successfully

Status	Branch	Result
✅	8.17

Questions ?

Please refer to the Backport tool documentation