Document passing Repo.get_dynamic_repo(), closes #701

Author: josevalim

lib/ecto/adapters/sql.ex

@@ -39,9 +39,11 @@ defmodule Ecto.Adapters.SQL do
 
   Generally speaking, you must invoke those functions directly from
   your repository, for example: `MyApp.Repo.query("SELECT true")`.
+
   You can also invoke them directly from `Ecto.Adapters.SQL`, but
-  keep in mind that in such cases features such as "dynamic repositories"
-  won't be available.
+  keep in mind that in such cases the "dynamic repository" functionality
+  is not available by default. Instead, you must explicitly call
+  `YouRepo.get_dynamic_repo()` and pass it as first argument.
 
   ## Migrations
 
@@ -319,17 +321,20 @@ defmodule Ecto.Adapters.SQL do
 
   If the query was successful, it will return an `:ok` tuple containing
   a map with at least two keys:
+
     * `:num_rows` - the number of rows affected
     * `:rows` - the result set as a list. `nil` may be returned
       instead of the list if the command does not yield any row
       as result (but still yields the number of affected rows,
       like a `delete` command without returning would)
 
   ## Options
+
     * `:log` - When false, does not log the query
     * `:timeout` - Execute request timeout, accepts: `:infinity` (default: `#{@timeout}`);
 
   ## Examples
+
       iex> MyRepo.query("SELECT $1::integer + $2", [40, 2])
       {:ok, %{rows: [[42]], num_rows: 1}}