Fix markdown spacing in various docs

doc/user/group/index.md

doc/user/group/saml_sso/scim_setup.md

doc/user/project/file_lock.md

doc/user/project/import/bitbucket.md

doc/user/project/import/bitbucket_server.md

doc/user/project/import/gemnasium.md

doc/user/project/import/manifest.md

doc/user/project/integrations/mattermost_slash_commands.md

doc/user/project/integrations/redmine.md

doc/user/project/members/share_project_with_groups.md

doc/user/project/merge_requests/merge_request_approvals.md

...domains_ssl_tls_certification/lets_encrypt_integration.md

doc/user/project/pages/getting_started_part_two.md

doc/user/project/pages/index.md

doc/user/project/protected_branches.md

doc/user/project/protected_tags.md