Bump up document site version

• api.go.cd
• plugin-api.go.cd
• developer.go.cd
• docs.go.cd

To bump up above mentioned document site version run following command -

bundle install --path .bundle --binstubs
ORG=bdpiparva REPO_NAME=plugin-api.go.cd GITHUB_USER=foo GITHUB_TOKEN=bar NEXT_VERSION=18.12.0 VERSION_TO_RELEASE=18.11.0 bundle exec rake bump_docs_version

On build.gocd.org download version.json file from installers pipeline using fetch artifact task. Setup following environment variables at pipeline level

ORG=bdpiparva 
GITHUB_USER=foo 
GITHUB_TOKEN=bar 
NEXT_VERSION=18.12.0 

Create a job with following task -

bundle install --path .bundle --binstubs
REPO_NAME=plugin-api.go.cd bundle exec rake bump_docs_version

Note: Here script is reading VERSION_TO_RELEASE from version.json file