Merge pull request #65 from mdaliejaz/gh-pages

Updated gitbook with latest changes
Update gitbook for 'Personalize Pipelines'.

Related to: https://github.com/gocd/documentation/pull/66
Merge pull request #67 from arvindsv/gh-pages

Update gitbook for 'Personalize Pipelines'.
Update gitbook for 'Pipeline Comment' feature.

Related to: https://github.com/gocd/documentation/pull/68
Merge pull request #69 from arvindsv/gh_pages_pipeline_comment

Update gitbook for 'Pipeline Comment' feature.