Add ability to sync from wiki 👉 repo

[jcbhmr]

See #65. @jcbhmr is willing to implement this, even if a bit reulctantly.

cc @floydwilde @Andrew-Chen-Wang

[Andrew-Chen-Wang]

Sounds cool, but this might be another action that auto commits/auto generates a PR which is up to the dev's discretion. Adding an example folder suffices.

[ReenigneArcher]

I accomplished this with the following workflow.

This assumes the wiki is contained in a wiki directory. If you use docs the workflow will need a few tweaks.

---
name: "Pull wiki"

on:
  gollum  # When wiki is updated

concurrency:
  group: "${{ github.workflow }}"
  cancel-in-progress: true

jobs:
  publish:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Clean wiki
        run: rm -rf wiki

      - name: Checkout wiki
        run: git clone https://github.com/${{ github.repository }}.wiki.git wiki --depth 1

      - name: Remove wiki git
        run: rm -rf wiki/.git

      - name: git diff
        id: diff
        run: |
          git add ./wiki/*
          git diff --staged
          git diff --color

          # multi-line output
          echo "diff<<EOF" >> $GITHUB_OUTPUT
          git diff >> $GITHUB_OUTPUT
          echo "EOF" >> $GITHUB_OUTPUT

          if [[ -n "$(git diff --staged)" ]]; then
            echo "Changes detected"
            echo "diff<<EOF" >> $GITHUB_OUTPUT
            git diff --staged >> $GITHUB_OUTPUT
            echo "EOF" >> $GITHUB_OUTPUT
            echo "has_changes=true" >> $GITHUB_OUTPUT
          else
            echo "No changes detected"
            echo "has_changes=false" >> $GITHUB_OUTPUT
          fi

      - name: Create/Update Pull Request
        id: create-pr
        if: steps.diff.outputs.has_changes == 'true'
        uses: peter-evans/create-pull-request@v7
        with:
          add-paths: |
            wiki/**
          token: ${{ secrets.GITHUB_TOKEN }}
          commit-message: "chore: sync wiki"
          branch: bot/sync-wiki
          delete-branch: true
          title: "chore: sync wiki"
          body: |
            This PR syncs the wiki with the main repository.

      - name: Automerge PR
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        if: steps.create-pr.outputs.pull-request-number != ''
        run: |
          gh \
            pr \
            merge \
            --auto \
            --delete-branch \
            --squash \
            "${{ steps.create-pr.outputs.pull-request-number }}"