Indent code blocks to put them inside the list item

Put the code blocks inside the list item to fix the item number which
was always "1" since Redcarpet creates a new "ul" each time a paragraph
is added.
Add a note about the DSN with the reverse command

The DSN is still explained for each supported RDBMS in the runtime
configuration reference guide. Refs propelorm/Propel2#554.
Add a new line to make the list parsed