Update documentation

Author: Zurga

lib/ecto/migration.ex

@@ -276,13 +276,12 @@ defmodule Ecto.Migration do
 
   ## Collations
 
-  For columns with a text type, the collation can be set on the column with the
-  option `:collation`. This can be useful when relying on ASCII sorting of
-  characters when using a fractional index for example. All supported collations
-  are not known by `ecto_sql` and specifying an incorrect collation might cause
-  a migration to fail.
-
-  ### N.B. be sure to match the collation on any columns that reference other text columns. See example below
+  Collations can be set on a column with the option `:collation`. This can be
+  useful when relying on ASCII sorting of characters when using a fractional index
+  for example. All supported collations and types that suuport setting a collocation
+  are not known by `ecto_sql` and specifying an incorrect collation or a collation on
+  an unsupported type might cause a migration to fail. Be sure to match the collation
+  on any column that references another column.
 
       def change do
         create table(:collate_reference) do