Docs: Merge Various EE /doc dirs to CE

doc/articles/how_to_configure_ldap_gitlab_ee/index.md

doc/getting-started/subscription.md

doc/git_hooks/git_hooks.md

doc/gitlab-basics/create-project.md

doc/install/ldap.md

doc/install/pivotal/index.md

doc/install/requirements.md

doc/legal/corporate_contributor_license_agreement.md

doc/legal/individual_contributor_license_agreement.md

doc/license/README.md

doc/raketasks/cleanup.md

doc/subscriptions/billing_table.png

doc/subscriptions/index.md

doc/tools/email.md

doc/tools/email1.png

doc/tools/email2.png

doc/topics/authentication/index.md

doc/topics/autodevops/index.md

scripts/lint-doc.sh