Fix multi-line DSL options in reactor cheat sheet docs

[zachdaniel]

When running mix docs we get a bunch of these warnings from spark telling us to move our docs out of the reference and into something else. Either we need to loosen this restriction or we need to address it.

warning: Multi-line DSL option doc detected. Please move contextual information into the
doc of a section, entity or module.
What to do when the reactor is undoing it's work?

* `always` - The undo action will always be run.
* `never` - The action will never be undone.
* `outside_transaction` - The action will only be undone if not running inside a transaction.

  (spark 2.1.7) lib/spark/cheat_sheet.ex:286: Spark.CheatSheet.escape_pipes/1
  (spark 2.1.7) lib/spark/cheat_sheet.ex:266: anonymous fn/2 in Spark.CheatSheet.do_options_table/3
  (elixir 1.16.2) lib/enum.ex:1801: anonymous fn/2 in Enum.map_join/3
  (elixir 1.16.2) lib/enum.ex:4378: Enum.map_intersperse_list/3
  (elixir 1.16.2) lib/enum.ex:4381: Enum.map_intersperse_list/3
  (elixir 1.16.2) lib/enum.ex:1801: Enum.map_join/3