feat: add OpenAPI shcema to custom rest backend

[popsiclexu]

Closes #

📑 Description

add OpenAPI shcema to custom rest backend tutorial
Relative PR: k8sgpt-ai/k8sgpt#1228

✅ Checks

• My pull request adheres to the code style of this project
• My code requires changes to the documentation
• I have updated the documentation as required
• All the tests have passed

ℹ Additional Information

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[PixelRobots]

Hey @popsiclexu You are missing DCO from this pull request. Can you please look at the instructions below to sign off this commit.

To sign off the last commit you made, you can use

git commit --amend --signoff

You can also automate signing off your commits by adding the following to your .zshrc or .bashrc:

git() {
  if [ $# -gt 0 ] && [[ "$1" == "commit" ]] ; then
     shift
     command git commit --signoff "$@"
  else
     command git "$@"
  fi
}

[popsiclexu]

@PixelRobots I have already signed the commit. Thanks for pointing it out!

[PixelRobots]

Hey thanks for that. It looks like the commit also needs a verified signature before I can merge it.

Below you will find some instructions on how this can be fixed.

1. Check If Your Commits Are Signed

Run this in your terminal:

git log --show-signature

If your commits are not signed or marked as unverified, proceed to the next step.

2. Set Up GPG or SSH Key Signing

For GPG Signing (Recommended)

1. Generate a GPG Key (if you don’t have one)

   gpg --full-generate-key

   • Choose RSA and RSA.
   • Select a key size of at least 4096 bits.
   • Set an expiration date (or choose no expiration).
   • Enter your GitHub email when prompted.

2. List Your GPG Keys

   gpg --list-secret-keys --keyid-format=long

   Copy the GPG key ID from the output.

3. Export Your Public Key

   gpg --armor --export YOUR_KEY_ID

   • Copy the output and add it to GitHub under:
     GitHub Settings > SSH and GPG keys > New GPG Key.

4. Tell Git to Use Your GPG Key

   git config --global user.signingkey YOUR_KEY_ID
   git config --global commit.gpgsign true

5. Sign Your Commits

   git commit -S -m "Your commit message"

6. Push the Signed Commit

   git push origin YOUR_BRANCH

For SSH Signing (Alternative)

If you're using SSH, follow [GitHub’s SSH commit signing guide](https://docs.github.com/en/authentication/managing-commit-signature-verification/generating-a-new-ssh-key-for-commit-signing).

After signing, your commits should show as "Verified" in GitHub and I will be able to merge.

Thanks again for your contribution.

[popsiclexu]

@PixelRobots I have already signed the commit. Thanks for your help.

[PixelRobots]

LGTM