Fixes broken table layout

Closes https://gitlab.com/gitlab-com/gitlab-docs/issues/176

Review apps: http://fix-responsive-table.178.62.207.141.xip.io/ee/user/project/integrations/prometheus_library/kubernetes.html#requirements

@joshlambert this MR fixes the all the tables but doesn't solve your problem on that doc:

We'll need to add the code to code blocks. We can't do it with tables in plain markdown, so I'll submit another MR (https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/18028) to the doc itself to make them readable.