Formatting changes for the MAILING-LIST-SETUP doc

Added some formatting changes for the MAILING-LIST-SETUP doc to make it
easier to read.
Delete enable_local_account_create option as it is not used anywhere.

JS fixture
Improve plugins.md text
Merge pull request #2191 from willkara/doc-edits

Formatting changes for the MAILING-LIST-SETUP doc
Merge pull request #2196 from riking/patch-1

Improve plugins.md text
Merge pull request #2193 from slainer68/delete_enable_local_account_create

Delete enable_local_account_create option as it is not used anywhere.