azure: Remove job generating documentation

With the recent addition of GitHub Actions to our CI infrastructure, we
now have two jobs which generate documentation: once in GHA, once in
Azure. Naturally, as they both want to update the same branch, they race
against each other and one of both jobs will fail.

Fix this by removing the documentation job from Azure.

azure-pipelines.yml

@@ -151,40 +151,3 @@ jobs:
         CMAKE_OPTIONS: -DDEPRECATE_HARD=ON
         SKIP_SSH_TESTS: true
         SKIP_NEGOTIATE_TESTS: true
-
-- job: documentation
-  displayName: 'Generate Documentation'
-  pool:
-    vmImage: 'ubuntu-18.04'
-  steps:
-  - script: |
-      cd $(Build.SourcesDirectory)/azure-pipelines/docker
-      docker build -t libgit2/docurium --build-arg BASE=ubuntu:trusty -f docurium .
-    displayName: 'Build Docker image'
-  - script: |
-      git config user.name 'Documentation Generation'
-      git config user.email 'libgit2@users.noreply.github.com'
-      git branch gh-pages origin/gh-pages
-      docker run --rm -v $(Build.SourcesDirectory):/home/libgit2/source -w /home/libgit2/source libgit2/docurium:latest cm doc api.docurium
-      git checkout gh-pages
-      cp -R * '$(Build.BinariesDirectory)'
-    displayName: 'Generate Documentation'
-  - task: archivefiles@2
-    displayName: 'Archive Documentation'
-    inputs:
-      rootFolderOrFile: '$(Build.BinariesDirectory)'
-      includeRootFolder: false
-      archiveFile: '$(Build.ArtifactStagingDirectory)/api-documentation.zip'
-  - task: publishbuildartifacts@1
-    displayName: 'Upload Documentation Artifact'
-    inputs:
-      pathToPublish: '$(Build.ArtifactStagingDirectory)'
-      artifactName: 'docs'
-  - script: |
-      git remote -v
-      echo 'machine github.com' > ~/.netrc
-      echo 'login $(GITHUB_USERNAME)' >> ~/.netrc
-      echo 'password $(GITHUB_PAT)' >> ~/.netrc
-      git push origin gh-pages
-    displayName: 'Publish Documentation'
-    condition: and(eq(variables['Build.Repository.Name'], 'libgit2/libgit2'), eq(variables['Build.Reason'], 'IndividualCI'))