Update section "Run the installer" (D7/BD)

* There are two distinct workflows, web-based and CLI-based. Put them in collapsible admonitions.
* For web-based flow, use "activate-first" / "civicrm-setup" workflow instead of
  the `sites/all/modules/civicrm/install/yaddayadda` workflow
* Remove older warning module-activation. It's no longer a bad thing if an admin
  activates on their own accord.