.github/workflows: disable updating VictoriaMetrics wiki with docs

The https://github.com/VictoriaMetrics/VictoriaMetrics/wiki has been broken and unmaintained
after VictoriaMetrics documentation has been moved to https://docs.victoriametrics.com .

Let's remove the broken GitHub action, which tries keeping in sync VictoriaMetrics wiki at https://github.com/VictoriaMetrics/VictoriaMetrics/wiki .

.github/workflows/wiki.yml

@@ -1,28 +0,0 @@
-name: wiki
-on:
-  push:
-    paths:
-      - 'docs/*'
-    branches:
-      - master
-jobs:
-  build:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@master
-      - name: publish
-        shell: bash
-        env:
-          TOKEN: ${{secrets.CI_TOKEN}}
-        run: |
-          git clone https://vika:${TOKEN}@github.com/VictoriaMetrics/VictoriaMetrics.wiki.git wiki
-          cp -r docs/* wiki
-          cd wiki
-          git config --local user.email "info@victoriametrics.com"
-          git config --local user.name "Vika"
-          git add .
-          git commit -m "update wiki pages"
-          remote_repo="https://vika:${TOKEN}@github.com/VictoriaMetrics/VictoriaMetrics.wiki.git"
-          git push "${remote_repo}"
-          cd ..
-          rm -rf wiki