Merge pull request rails#48021 from p8/docs/headers-active-model-types

Add some missing headers to Active Model Type docs [ci-skip]

Author: p8

activemodel/lib/active_model/type/big_integer.rb

@@ -4,6 +4,8 @@
 
 module ActiveModel
   module Type
+    # Active Model \BigInteger \Type
+    #
     # Attribute type for integers that can be serialized to an unlimited number
     # of bytes. This type is registered under the +:big_integer+ key.
     #

activemodel/lib/active_model/type/binary.rb

@@ -2,6 +2,8 @@
 
 module ActiveModel
   module Type
+    # Active Model \Binary \Type
+    #
     # Attribute type for representation of binary data. This type is registered
     # under the +:binary+ key.
     #

activemodel/lib/active_model/type/boolean.rb

@@ -2,6 +2,8 @@
 
 module ActiveModel
   module Type
+    # Active Model \Boolean \Type
+    #
     # A class that behaves like a boolean type, including rules for coercion of
     # user input.
     #

activemodel/lib/active_model/type/date.rb

@@ -2,6 +2,8 @@
 
 module ActiveModel
   module Type
+    # Active Model \Date \Type
+    #
     # Attribute type for date representation. It is registered under the
     # +:date+ key.
     #

activemodel/lib/active_model/type/date_time.rb

@@ -2,6 +2,8 @@
 
 module ActiveModel
   module Type
+    # Active Model \DateTime \Type
+    #
     # Attribute type to represent dates and times. It is registered under the
     # +:datetime+ key.
     #

activemodel/lib/active_model/type/decimal.rb

@@ -4,6 +4,8 @@
 
 module ActiveModel
   module Type
+    # Active Model \Decimal \Type
+    #
     # Attribute type for decimal, high-precision floating point numeric
     # representation. It is registered under the +:decimal+ key.
     #

activemodel/lib/active_model/type/float.rb

@@ -4,6 +4,8 @@
 
 module ActiveModel
   module Type
+    # Active Model \Float \Type
+    #
     # Attribute type for floating point numeric values. It is registered under
     # the +:float+ key.
     #

activemodel/lib/active_model/type/immutable_string.rb

@@ -2,6 +2,8 @@
 
 module ActiveModel
   module Type
+    # Active Model \ImmutableString \Type
+    #
     # Attribute type to represent immutable strings. It casts incoming values to
     # frozen strings.
     #

activemodel/lib/active_model/type/integer.rb

@@ -2,6 +2,8 @@
 
 module ActiveModel
   module Type
+    # Active Model \Integer \Type
+    #
     # Attribute type for integer representation. This type is registered under
     # the +:integer+ key.
     #

activemodel/lib/active_model/type/string.rb

@@ -4,6 +4,8 @@
 
 module ActiveModel
   module Type
+    # Active Model \String \Type
+    #
     # Attribute type for strings. It is registered under the +:string+ key.
     #
     # This class is a specialization of ActiveModel::Type::ImmutableString. It